diff --git a/README.md b/README.md
index b459130f..ca70a595 100644
--- a/README.md
+++ b/README.md
@@ -24,9 +24,9 @@ Queryosity is a row-wise data analysis library for (semi-)structured data.
 #include <sstream>
 #include <vector>
 
-#include "queryosity.h"
-#include "queryosity/hist.h"
-#include "queryosity/json.h"
+#include <queryosity.hpp>
+#include <queryosity/hist.hpp>
+#include <queryosity/json.hpp>
 
 using dataflow = qty::dataflow;
 namespace multithread = qty::multithread;
@@ -68,7 +68,7 @@ int main() {
 
 ### [Single-header](https://raw.githubusercontent.com/taehyounpark/queryosity/master/queryosity.h)
 ```cpp
-#include "queryosity.h"
+#include <queryosity.hpp>
 ```
 ### CMake
 ```sh
@@ -89,7 +89,7 @@ add_library(Analysis ...)
 target_link_libraries(Analysis INTERFACE queryosity::queryosity)
 ```
 ```cpp
-#include "queryosity.h"
+#include <queryosity.hpp>
 ```
 #### Integrated
 ```cmake
diff --git a/docs/examples/hello.md b/docs/examples/hello.md
index 57f57388..3f5ca295 100644
--- a/docs/examples/hello.md
+++ b/docs/examples/hello.md
@@ -14,9 +14,9 @@
 #include <sstream>
 #include <vector>
 
-#include "queryosity.h"
+#include <queryosity.hpp>
 #include "queryosity/hist.h"
-#include "queryosity/json.h"
+#include <queryosity/json.hpp>
 
 using dataflow = qty::dataflow;
 namespace multithread = qty::multithread;
diff --git a/docs/examples/hww.md b/docs/examples/hww.md
index bcbb60f5..39055890 100644
--- a/docs/examples/hww.md
+++ b/docs/examples/hww.md
@@ -14,7 +14,7 @@
 #include "AnaQuery/Hist.h"
 #include "AnaQuery/Tree.h"
 
-#include "queryosity.h"
+#include <queryosity.hpp>
 
 namespace qty = queryosity;
 using dataflow = qty::dataflow;
diff --git a/docs/examples/iris.md b/docs/examples/iris.md
index a4eead70..7c949166 100644
--- a/docs/examples/iris.md
+++ b/docs/examples/iris.md
@@ -9,7 +9,7 @@
 #include <cstdlib>
 #include <functional>
 
-#include "queryosity.h"
+#include <queryosity.hpp>
 
 #include "TCanvas.h"
 #include <ROOT/RVec.hxx>
diff --git a/docs/examples/xaod.md b/docs/examples/xaod.md
index f59d6b30..5b2f74dc 100644
--- a/docs/examples/xaod.md
+++ b/docs/examples/xaod.md
@@ -14,7 +14,7 @@
 using VecF = ROOT::RVec<float>;
 using VecD = ROOT::RVec<double>;
 
-#include "queryosity.h"
+#include <queryosity.hpp>
 
 using dataflow = qty::dataflow;
 namespace multithread = qty::multithread;
diff --git a/docs/guide/columns.md b/docs/guide/columns.md
index be598d4c..7bba5252 100644
--- a/docs/guide/columns.md
+++ b/docs/guide/columns.md
@@ -86,9 +86,9 @@ Consider the following example of computing the factorial of a number, $ n! = 1
 #include <sstream>
 #include <vector>
 
-#include "queryosity.h"
+#include <queryosity.hpp>
 #include "queryosity/hist.h"
-#include "queryosity/json.h"
+#include <queryosity/json.hpp>
 
 using dataflow = qty::dataflow;
 namespace multithread = qty::multithread;
diff --git a/docs/guide/dataflow.md b/docs/guide/dataflow.md
index c22adeb7..6756cb6c 100644
--- a/docs/guide/dataflow.md
+++ b/docs/guide/dataflow.md
@@ -1,7 +1,7 @@
 # Dataflow
 
 ```cpp
-#include "queryosity.h"
+#include <queryosity.hpp>
 
 using dataflow = qty::dataflow;
 namespace multithread = qty::multithread;
diff --git a/docs/start/install.md b/docs/start/install.md
index 074a6f18..0eaea09e 100644
--- a/docs/start/install.md
+++ b/docs/start/install.md
@@ -16,7 +16,7 @@
 ## Single-header
 
 ```cpp
-#include "queryosity.h"
+#include <queryosity.hpp>
 ```
 
 ## CMake
@@ -43,7 +43,7 @@ target_link_libraries(MyAnalysis INTERFACE queryosity::queryosity)
 ```
 
 ```cpp
-#include "queryosity.h"
+#include <queryosity.hpp>
 ```
 
 ### Integrated
@@ -57,5 +57,5 @@ target_link_libraries(MyAnalysis INTERFACE queryosity::queryosity)
 ```
 
 ```cpp
-#include "queryosity.h"
+#include <queryosity.hpp>
 ```
diff --git a/examples/example-01.cxx b/examples/example-01.cxx
index 5e039d8d..9c212120 100644
--- a/examples/example-01.cxx
+++ b/examples/example-01.cxx
@@ -2,9 +2,9 @@
 #include <sstream>
 #include <vector>
 
-#include "queryosity.h"
+#include <queryosity.hpp>
 #include "queryosity/hist.h"
-#include "queryosity/json.h"
+#include <queryosity/json.hpp>
 
 using dataflow = qty::dataflow;
 namespace multithread = qty::multithread;
diff --git a/examples/example-02.cxx b/examples/example-02.cxx
index 917b4691..fb99574d 100644
--- a/examples/example-02.cxx
+++ b/examples/example-02.cxx
@@ -2,10 +2,10 @@
 #include <sstream>
 #include <vector>
 
-#include "queryosity.h"
+#include <queryosity.hpp>
 #include "queryosity/hist.h"
-#include "queryosity/json.h"
-#include "queryosity/csv.h"
+#include <queryosity/json.hpp>
+#include <queryosity/csv.hpp>
 
 using dataflow = qty::dataflow;
 namespace multithread = qty::multithread;
diff --git a/examples/example-03.cxx b/examples/example-03.cxx
index 02ef9265..6e385a51 100644
--- a/examples/example-03.cxx
+++ b/examples/example-03.cxx
@@ -2,9 +2,9 @@
 #include <sstream>
 #include <vector>
 
-#include "queryosity.h"
+#include <queryosity.hpp>
 #include "queryosity/hist.h"
-#include "queryosity/json.h"
+#include <queryosity/json.hpp>
 
 using dataflow = qty::dataflow;
 namespace multithread = qty::multithread;
diff --git a/extensions/CMakeLists.txt b/extensions/CMakeLists.txt
index b2e77c67..e6145243 100644
--- a/extensions/CMakeLists.txt
+++ b/extensions/CMakeLists.txt
@@ -1,4 +1,4 @@
-file(GLOB QUERYOSITY_EXT_HEADERS ${CMAKE_CURRENT_SOURCE_DIR}/queryosity/*.h)
+file(GLOB QUERYOSITY_EXT_HEADERS ${CMAKE_CURRENT_SOURCE_DIR}/queryosity/*.hpp)
 add_library(
   queryosity_extensions
   SHARED
diff --git a/extensions/queryosity/csv.h b/extensions/queryosity/csv.hpp
similarity index 99%
rename from extensions/queryosity/csv.h
rename to extensions/queryosity/csv.hpp
index 6e9534af..49bc7b12 100644
--- a/extensions/queryosity/csv.h
+++ b/extensions/queryosity/csv.hpp
@@ -1,6 +1,6 @@
 #include "rapidcsv.h"
 
-#include "queryosity.h"
+#include <queryosity.hpp>
 
 namespace queryosity {
 
diff --git a/extensions/queryosity/hist.h b/extensions/queryosity/hist.hpp
similarity index 99%
rename from extensions/queryosity/hist.h
rename to extensions/queryosity/hist.hpp
index 9aaf4f6f..1e4fd306 100644
--- a/extensions/queryosity/hist.h
+++ b/extensions/queryosity/hist.hpp
@@ -1,4 +1,4 @@
-#include "queryosity.h"
+#include <queryosity.hpp>
 
 #include <boost/histogram.hpp> // make_histogram, regular, weight, indexed
 #include <boost/histogram/ostream.hpp>
diff --git a/extensions/queryosity/json.h b/extensions/queryosity/json.hpp
similarity index 99%
rename from extensions/queryosity/json.h
rename to extensions/queryosity/json.hpp
index c4572a41..9f21ec48 100644
--- a/extensions/queryosity/json.h
+++ b/extensions/queryosity/json.hpp
@@ -3,7 +3,7 @@
 
 #include <nlohmann/json.hpp>
 
-#include "queryosity.h"
+#include <queryosity.hpp>
 
 namespace queryosity {
 
diff --git a/extensions/queryosity/wsum.h b/extensions/queryosity/wsum.hpp
similarity index 96%
rename from extensions/queryosity/wsum.h
rename to extensions/queryosity/wsum.hpp
index d54da66a..f7c73428 100644
--- a/extensions/queryosity/wsum.h
+++ b/extensions/queryosity/wsum.hpp
@@ -4,7 +4,7 @@
 #include <unordered_map>
 #include <variant>
 
-#include "queryosity.h"
+#include <queryosity.hpp>
 
 namespace queryosity {
 
diff --git a/include/queryosity.h b/include/queryosity.h
deleted file mode 100644
index 148f4c66..00000000
--- a/include/queryosity.h
+++ /dev/null
@@ -1,31 +0,0 @@
-#pragma once
-
-/**
- * @defgroup ext Extensions
- * @defgroup api API
- * @defgroup abc ABCs
- */
-
-#include "queryosity/multithread.h"
-
-#include "queryosity/dataset_reader.h"
-
-#include "queryosity/column_definition.h"
-#include "queryosity/column_equation.h"
-#include "queryosity/column_reader.h"
-#include "queryosity/column_series.h"
-
-#include "queryosity/selection_yield.h"
-
-#include "queryosity/query_aggregation.h"
-#include "queryosity/query_definition.h"
-#include "queryosity/query_series.h"
-
-#include "queryosity/dataflow.h"
-
-#include "queryosity/lazy.h"
-#include "queryosity/lazy_varied.h"
-#include "queryosity/todo.h"
-#include "queryosity/todo_varied.h"
-
-namespace qty = queryosity;
\ No newline at end of file
diff --git a/include/queryosity.hpp b/include/queryosity.hpp
new file mode 100644
index 00000000..50a4f24a
--- /dev/null
+++ b/include/queryosity.hpp
@@ -0,0 +1,31 @@
+#pragma once
+
+/**
+ * @defgroup ext Extensions
+ * @defgroup api API
+ * @defgroup abc ABCs
+ */
+
+#include "queryosity/multithread.hpp"
+
+#include "queryosity/dataset_reader.hpp"
+
+#include "queryosity/column_definition.hpp"
+#include "queryosity/column_equation.hpp"
+#include "queryosity/column_reader.hpp"
+#include "queryosity/column_series.hpp"
+
+#include "queryosity/selection_yield.hpp"
+
+#include "queryosity/query_aggregation.hpp"
+#include "queryosity/query_definition.hpp"
+#include "queryosity/query_series.hpp"
+
+#include "queryosity/dataflow.hpp"
+
+#include "queryosity/lazy.hpp"
+#include "queryosity/lazy_varied.hpp"
+#include "queryosity/todo.hpp"
+#include "queryosity/todo_varied.hpp"
+
+namespace qty = queryosity;
\ No newline at end of file
diff --git a/include/queryosity/action.h b/include/queryosity/action.hpp
similarity index 98%
rename from include/queryosity/action.h
rename to include/queryosity/action.hpp
index 0b474061..66dc2d8c 100644
--- a/include/queryosity/action.h
+++ b/include/queryosity/action.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "systematic.h"
+#include "systematic.hpp"
 
 #include <string>
 
diff --git a/include/queryosity/column.h b/include/queryosity/column.hpp
similarity index 99%
rename from include/queryosity/column.h
rename to include/queryosity/column.hpp
index a84222d7..de6afac4 100644
--- a/include/queryosity/column.h
+++ b/include/queryosity/column.hpp
@@ -4,7 +4,7 @@
 #include <memory>
 #include <type_traits>
 
-#include "action.h"
+#include "action.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/column_calculation.h b/include/queryosity/column_calculation.hpp
similarity index 99%
rename from include/queryosity/column_calculation.h
rename to include/queryosity/column_calculation.hpp
index d0a4c40b..4806ddc9 100644
--- a/include/queryosity/column_calculation.h
+++ b/include/queryosity/column_calculation.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "column.h"
+#include "column.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/column_composition.h b/include/queryosity/column_composition.hpp
similarity index 98%
rename from include/queryosity/column_composition.h
rename to include/queryosity/column_composition.hpp
index c17864e5..918bca3a 100644
--- a/include/queryosity/column_composition.h
+++ b/include/queryosity/column_composition.hpp
@@ -4,7 +4,7 @@
 #include <memory>
 #include <tuple>
 
-#include "column.h"
+#include "column.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/column_computation.h b/include/queryosity/column_computation.hpp
similarity index 93%
rename from include/queryosity/column_computation.h
rename to include/queryosity/column_computation.hpp
index bda9f6db..16b17e7c 100644
--- a/include/queryosity/column_computation.h
+++ b/include/queryosity/column_computation.hpp
@@ -5,8 +5,8 @@
 #include <type_traits>
 #include <vector>
 
-#include "column.h"
-#include "dataset.h"
+#include "column.hpp"
+#include "dataset.hpp"
 
 namespace queryosity {
 
@@ -50,11 +50,11 @@ class computation {
 
 } // namespace queryosity
 
-#include "column_conversion.h"
-#include "column_equation.h"
-#include "column_evaluator.h"
-#include "column_fixed.h"
-#include "dataset_reader.h"
+#include "column_conversion.hpp"
+#include "column_equation.hpp"
+#include "column_evaluator.hpp"
+#include "column_fixed.hpp"
+#include "dataset_reader.hpp"
 
 template <typename DS, typename Val>
 auto queryosity::column::computation::read(dataset::reader<DS> &ds,
diff --git a/include/queryosity/column_constant.h b/include/queryosity/column_constant.hpp
similarity index 92%
rename from include/queryosity/column_constant.h
rename to include/queryosity/column_constant.hpp
index 947381ba..76d4d7bf 100644
--- a/include/queryosity/column_constant.h
+++ b/include/queryosity/column_constant.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "column.h"
+#include "column.hpp"
 
 namespace queryosity {
 
@@ -35,8 +35,8 @@ template <typename Val> struct constant {
 
 } // namespace queryosity
 
-#include "dataflow.h"
-#include "lazy.h"
+#include "dataflow.hpp"
+#include "lazy.hpp"
 
 template <typename Val>
 queryosity::column::constant<Val>::constant(Val const &val) : m_val(val) {}
diff --git a/include/queryosity/column_conversion.h b/include/queryosity/column_conversion.hpp
similarity index 92%
rename from include/queryosity/column_conversion.h
rename to include/queryosity/column_conversion.hpp
index 4144bf23..fcc205ca 100644
--- a/include/queryosity/column_conversion.h
+++ b/include/queryosity/column_conversion.hpp
@@ -3,8 +3,8 @@
 #include <memory>
 #include <tuple>
 
-#include "column.h"
-#include "column_definition.h"
+#include "column.hpp"
+#include "column_definition.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/column_definition.h b/include/queryosity/column_definition.hpp
similarity index 95%
rename from include/queryosity/column_definition.h
rename to include/queryosity/column_definition.hpp
index 3578077b..e6bef5cb 100644
--- a/include/queryosity/column_definition.h
+++ b/include/queryosity/column_definition.hpp
@@ -3,9 +3,9 @@
 #include <memory>
 #include <tuple>
 
-#include "column_calculation.h"
-#include "column_evaluator.h"
-#include "todo.h"
+#include "column_calculation.hpp"
+#include "column_evaluator.hpp"
+#include "todo.hpp"
 
 namespace queryosity {
 
@@ -69,7 +69,7 @@ template <typename Def> class column::definition {
 
 } // namespace queryosity
 
-#include "dataflow.h"
+#include "dataflow.hpp"
 
 template <typename Out, typename... Ins>
 template <typename... Args>
diff --git a/include/queryosity/column_equation.h b/include/queryosity/column_equation.hpp
similarity index 98%
rename from include/queryosity/column_equation.h
rename to include/queryosity/column_equation.hpp
index e9a90903..7406c2f9 100644
--- a/include/queryosity/column_equation.h
+++ b/include/queryosity/column_equation.hpp
@@ -2,7 +2,7 @@
 
 #include <functional>
 
-#include "column_definition.h"
+#include "column_definition.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/column_evaluator.h b/include/queryosity/column_evaluator.hpp
similarity index 97%
rename from include/queryosity/column_evaluator.h
rename to include/queryosity/column_evaluator.hpp
index 45357370..793ee239 100644
--- a/include/queryosity/column_evaluator.h
+++ b/include/queryosity/column_evaluator.hpp
@@ -4,7 +4,7 @@
 #include <memory>
 #include <type_traits>
 
-#include "action.h"
+#include "action.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/column_expression.h b/include/queryosity/column_expression.hpp
similarity index 93%
rename from include/queryosity/column_expression.h
rename to include/queryosity/column_expression.hpp
index a35a9899..3b8b34a8 100644
--- a/include/queryosity/column_expression.h
+++ b/include/queryosity/column_expression.hpp
@@ -3,8 +3,8 @@
 #include <string>
 #include <tuple>
 
-#include "column.h"
-#include "column_equation.h"
+#include "column.hpp"
+#include "column_equation.hpp"
 
 namespace queryosity {
 
@@ -54,9 +54,9 @@ template <typename Expr> struct expression {
 
 } // namespace queryosity
 
-#include "dataflow.h"
-#include "lazy.h"
-#include "selection.h"
+#include "dataflow.hpp"
+#include "lazy.hpp"
+#include "selection.hpp"
 
 template <typename Expr>
 queryosity::column::expression<Expr>::expression(Expr expr)
diff --git a/include/queryosity/column_fixed.h b/include/queryosity/column_fixed.hpp
similarity index 98%
rename from include/queryosity/column_fixed.h
rename to include/queryosity/column_fixed.hpp
index 61164b4b..bb218ee6 100644
--- a/include/queryosity/column_fixed.h
+++ b/include/queryosity/column_fixed.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "column.h"
+#include "column.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/column_nominal.h b/include/queryosity/column_nominal.hpp
similarity index 94%
rename from include/queryosity/column_nominal.h
rename to include/queryosity/column_nominal.hpp
index d19ee7bc..66dc10fa 100644
--- a/include/queryosity/column_nominal.h
+++ b/include/queryosity/column_nominal.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "column.h"
+#include "column.hpp"
 
 namespace queryosity {
 
@@ -27,7 +27,7 @@ template <typename Col> struct nominal {
 
 } // namespace queryosity
 
-#include "lazy.h"
+#include "lazy.hpp"
 
 template <typename Col>
 queryosity::column::nominal<Col>::nominal(lazy<Col> const &nom) : m_nom(nom) {}
diff --git a/include/queryosity/column_reader.h b/include/queryosity/column_reader.hpp
similarity index 97%
rename from include/queryosity/column_reader.h
rename to include/queryosity/column_reader.hpp
index dc1b17f9..a24929e9 100644
--- a/include/queryosity/column_reader.h
+++ b/include/queryosity/column_reader.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "column.h"
+#include "column.hpp"
 
 namespace queryosity {
 
@@ -47,7 +47,7 @@ template <typename T> class reader : public valued<T> {
 
 } // namespace queryosity
 
-#include "dataset.h"
+#include "dataset.hpp"
 
 template <typename T>
 queryosity::column::reader<T>::reader()
diff --git a/include/queryosity/column_series.h b/include/queryosity/column_series.hpp
similarity index 90%
rename from include/queryosity/column_series.h
rename to include/queryosity/column_series.hpp
index 7d092cb2..50080322 100644
--- a/include/queryosity/column_series.h
+++ b/include/queryosity/column_series.hpp
@@ -1,11 +1,11 @@
 #pragma once
 
-#include "column.h"
-#include "dataflow.h"
-#include "lazy.h"
-#include "lazy_varied.h"
-#include "query_series.h"
-#include "selection.h"
+#include "column.hpp"
+#include "dataflow.hpp"
+#include "lazy.hpp"
+#include "lazy_varied.hpp"
+#include "query_series.hpp"
+#include "selection.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/column_variation.h b/include/queryosity/column_variation.hpp
similarity index 89%
rename from include/queryosity/column_variation.h
rename to include/queryosity/column_variation.hpp
index f80a1344..7e598a6a 100644
--- a/include/queryosity/column_variation.h
+++ b/include/queryosity/column_variation.hpp
@@ -4,9 +4,9 @@
 #include <string>
 #include <type_traits>
 
-#include "dataflow.h"
-#include "lazy.h"
-#include "column_definition.h"
+#include "dataflow.hpp"
+#include "lazy.hpp"
+#include "column_definition.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/dataflow.h b/include/queryosity/dataflow.hpp
similarity index 98%
rename from include/queryosity/dataflow.h
rename to include/queryosity/dataflow.hpp
index 930f081d..27de8219 100644
--- a/include/queryosity/dataflow.h
+++ b/include/queryosity/dataflow.hpp
@@ -7,15 +7,15 @@
 #include <utility>
 #include <vector>
 
-#include "column.h"
-#include "dataset.h"
-#include "dataset_partition.h"
-#include "dataset_player.h"
-#include "dataset_processor.h"
-#include "multithread.h"
-#include "query.h"
-#include "selection.h"
-#include "systematic.h"
+#include "column.hpp"
+#include "dataset.hpp"
+#include "dataset_partition.hpp"
+#include "dataset_player.hpp"
+#include "dataset_processor.hpp"
+#include "multithread.hpp"
+#include "query.hpp"
+#include "selection.hpp"
+#include "systematic.hpp"
 
 namespace queryosity {
 
@@ -411,21 +411,21 @@ class dataflow::node {
 
 } // namespace queryosity
 
-#include "dataset_input.h"
-#include "dataset_loaded.h"
-#include "dataset_player.h"
+#include "dataset_input.hpp"
+#include "dataset_loaded.hpp"
+#include "dataset_player.hpp"
 
-#include "lazy.h"
-#include "lazy_varied.h"
-#include "todo.h"
+#include "lazy.hpp"
+#include "lazy_varied.hpp"
+#include "todo.hpp"
 
-#include "column_constant.h"
-#include "column_expression.h"
-#include "column_nominal.h"
-#include "column_variation.h"
-#include "query_output.h"
+#include "column_constant.hpp"
+#include "column_expression.hpp"
+#include "column_nominal.hpp"
+#include "column_variation.hpp"
+#include "query_output.hpp"
 
-#include "systematic_resolver.h"
+#include "systematic_resolver.hpp"
 
 inline queryosity::dataflow::dataflow()
     : m_processor(multithread::disable()), m_weight(1.0), m_nrows(-1),
diff --git a/include/queryosity/dataset.h b/include/queryosity/dataset.hpp
similarity index 92%
rename from include/queryosity/dataset.h
rename to include/queryosity/dataset.hpp
index 260871b0..b714b169 100644
--- a/include/queryosity/dataset.h
+++ b/include/queryosity/dataset.hpp
@@ -9,7 +9,7 @@
 #include <utility>
 #include <vector>
 
-#include "multithread.h"
+#include "multithread.hpp"
 
 namespace queryosity {
 
@@ -56,5 +56,5 @@ struct weight {
 
 } // namespace queryosity
 
-#include "column.h"
-#include "dataset_reader.h"
+#include "column.hpp"
+#include "dataset_reader.hpp"
diff --git a/include/queryosity/dataset_column.h b/include/queryosity/dataset_column.hpp
similarity index 92%
rename from include/queryosity/dataset_column.h
rename to include/queryosity/dataset_column.hpp
index 09319649..2e8c3e1e 100644
--- a/include/queryosity/dataset_column.h
+++ b/include/queryosity/dataset_column.hpp
@@ -5,7 +5,7 @@
 #include <tuple>
 #include <utility>
 
-#include "dataset.h"
+#include "dataset.hpp"
 
 namespace queryosity {
 
@@ -34,8 +34,8 @@ template <typename Val> struct dataset::column {
 
 } // namespace queryosity
 
-#include "dataflow.h"
-#include "dataset_loaded.h"
+#include "dataflow.hpp"
+#include "dataset_loaded.hpp"
 
 template <typename Val>
 queryosity::dataset::column<Val>::column(const std::string &name)
diff --git a/include/queryosity/dataset_input.h b/include/queryosity/dataset_input.hpp
similarity index 97%
rename from include/queryosity/dataset_input.h
rename to include/queryosity/dataset_input.hpp
index fc370d5f..3c3e5f3a 100644
--- a/include/queryosity/dataset_input.h
+++ b/include/queryosity/dataset_input.hpp
@@ -2,7 +2,7 @@
 
 #include <memory>
 
-#include "dataset.h"
+#include "dataset.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/dataset_loaded.h b/include/queryosity/dataset_loaded.hpp
similarity index 93%
rename from include/queryosity/dataset_loaded.h
rename to include/queryosity/dataset_loaded.hpp
index 9114d41b..cd671219 100644
--- a/include/queryosity/dataset_loaded.h
+++ b/include/queryosity/dataset_loaded.hpp
@@ -2,8 +2,8 @@
 
 #include <map>
 
-#include "dataflow.h"
-#include "systematic.h"
+#include "dataflow.hpp"
+#include "systematic.hpp"
 
 namespace queryosity {
 
@@ -38,9 +38,9 @@ template <typename DS> class loaded {
 
 } // namespace queryosity
 
-#include "dataset_column.h"
-#include "lazy.h"
-#include "lazy_varied.h"
+#include "dataset_column.hpp"
+#include "lazy.hpp"
+#include "lazy_varied.hpp"
 
 template <typename DS>
 queryosity::dataset::loaded<DS>::loaded(queryosity::dataflow &df, DS &ds)
diff --git a/include/queryosity/dataset_partition.h b/include/queryosity/dataset_partition.hpp
similarity index 97%
rename from include/queryosity/dataset_partition.h
rename to include/queryosity/dataset_partition.hpp
index e9a38be3..37c4385c 100644
--- a/include/queryosity/dataset_partition.h
+++ b/include/queryosity/dataset_partition.hpp
@@ -9,8 +9,8 @@
 #include <string>
 #include <vector>
 
-#include "dataset.h"
-#include "multithread.h"
+#include "dataset.hpp"
+#include "multithread.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/dataset_player.h b/include/queryosity/dataset_player.hpp
similarity index 95%
rename from include/queryosity/dataset_player.h
rename to include/queryosity/dataset_player.hpp
index 2bfeb598..0cd63e25 100644
--- a/include/queryosity/dataset_player.h
+++ b/include/queryosity/dataset_player.hpp
@@ -1,7 +1,7 @@
 #pragma once
 
-#include "column_computation.h"
-#include "query_experiment.h"
+#include "column_computation.hpp"
+#include "query_experiment.hpp"
 
 namespace queryosity {
 
@@ -22,7 +22,7 @@ class player : public query::experiment {
 
 } // namespace queryosity
 
-#include "dataset_reader.h"
+#include "dataset_reader.hpp"
 
 inline void queryosity::dataset::player::play(
     std::vector<std::unique_ptr<source>> const &sources, double scale,
diff --git a/include/queryosity/dataset_processor.h b/include/queryosity/dataset_processor.hpp
similarity index 98%
rename from include/queryosity/dataset_processor.h
rename to include/queryosity/dataset_processor.hpp
index b95dd30a..0007b99b 100644
--- a/include/queryosity/dataset_processor.h
+++ b/include/queryosity/dataset_processor.hpp
@@ -1,8 +1,8 @@
 #pragma once
 
-#include "dataset.h"
-#include "dataset_player.h"
-#include "multithread.h"
+#include "dataset.hpp"
+#include "dataset_player.hpp"
+#include "multithread.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/dataset_reader.h b/include/queryosity/dataset_reader.hpp
similarity index 98%
rename from include/queryosity/dataset_reader.h
rename to include/queryosity/dataset_reader.hpp
index 806a54cf..bc513407 100644
--- a/include/queryosity/dataset_reader.h
+++ b/include/queryosity/dataset_reader.hpp
@@ -1,7 +1,7 @@
 #pragma once
 
-#include "action.h"
-#include "column.h"
+#include "action.hpp"
+#include "column.hpp"
 
 namespace queryosity {
 
@@ -113,7 +113,7 @@ using read_column_t =
         std::declval<unsigned int>(),
         std::declval<std::string const &>()))::element_type;
 
-#include "column_reader.h"
+#include "column_reader.hpp"
 
 inline void queryosity::dataset::source::initialize() {}
 
diff --git a/include/queryosity/detail.h b/include/queryosity/detail.hpp
similarity index 100%
rename from include/queryosity/detail.h
rename to include/queryosity/detail.hpp
diff --git a/include/queryosity/lazy.h b/include/queryosity/lazy.hpp
similarity index 98%
rename from include/queryosity/lazy.h
rename to include/queryosity/lazy.hpp
index 6b03c91d..00cd40ca 100644
--- a/include/queryosity/lazy.h
+++ b/include/queryosity/lazy.hpp
@@ -6,10 +6,10 @@
 #include <type_traits>
 #include <vector>
 
-#include "dataflow.h"
-#include "detail.h"
-#include "query.h"
-#include "systematic_resolver.h"
+#include "dataflow.hpp"
+#include "detail.hpp"
+#include "query.hpp"
+#include "systematic_resolver.hpp"
 
 namespace queryosity {
 
@@ -216,11 +216,11 @@ class lazy : public dataflow::node,
 
 } // namespace queryosity
 
-#include "column.h"
-#include "column_series.h"
-#include "lazy_varied.h"
-#include "query_series.h"
-#include "todo.h"
+#include "column.hpp"
+#include "column_series.hpp"
+#include "lazy_varied.hpp"
+#include "query_series.hpp"
+#include "todo.hpp"
 
 template <typename Action>
 template <typename Derived>
diff --git a/include/queryosity/lazy_varied.h b/include/queryosity/lazy_varied.hpp
similarity index 99%
rename from include/queryosity/lazy_varied.h
rename to include/queryosity/lazy_varied.hpp
index d59f2e38..620b6801 100644
--- a/include/queryosity/lazy_varied.h
+++ b/include/queryosity/lazy_varied.hpp
@@ -5,9 +5,9 @@
 #include <unordered_map>
 #include <utility>
 
-#include "detail.h"
-#include "lazy.h"
-#include "systematic_resolver.h"
+#include "detail.hpp"
+#include "lazy.hpp"
+#include "systematic_resolver.hpp"
 
 namespace queryosity {
 
@@ -128,7 +128,7 @@ class varied<lazy<Act>> : public dataflow::node,
 
 } // namespace queryosity
 
-#include "selection.h"
+#include "selection.hpp"
 
 template <typename Act>
 queryosity::varied<queryosity::lazy<Act>>::varied(queryosity::lazy<Act> nom)
diff --git a/include/queryosity/multithread.h b/include/queryosity/multithread.hpp
similarity index 100%
rename from include/queryosity/multithread.h
rename to include/queryosity/multithread.hpp
diff --git a/include/queryosity/query.h b/include/queryosity/query.hpp
similarity index 98%
rename from include/queryosity/query.h
rename to include/queryosity/query.hpp
index aebd0149..e81a3e1c 100644
--- a/include/queryosity/query.h
+++ b/include/queryosity/query.hpp
@@ -6,7 +6,7 @@
 #include <utility>
 #include <vector>
 
-#include "action.h"
+#include "action.hpp"
 
 /**
  * @brief All queryosity namespaces and classes.
@@ -119,8 +119,8 @@ struct result_of<Action, std::enable_if_t<query::is_aggregation_v<Action>>> {
 
 } // namespace queryosity
 
-#include "column.h"
-#include "selection.h"
+#include "column.hpp"
+#include "selection.hpp"
 
 inline queryosity::query::node::node() : m_scale(1.0), m_selection(nullptr) {}
 
diff --git a/include/queryosity/query_aggregation.h b/include/queryosity/query_aggregation.hpp
similarity index 95%
rename from include/queryosity/query_aggregation.h
rename to include/queryosity/query_aggregation.hpp
index be43ef86..618c294d 100644
--- a/include/queryosity/query_aggregation.h
+++ b/include/queryosity/query_aggregation.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "query.h"
+#include "query.hpp"
 
 namespace queryosity {
 
@@ -47,4 +47,4 @@ template <typename T> class query::aggregation : public node {
 
 } // namespace queryosity
 
-#include "selection.h"
\ No newline at end of file
+#include "selection.hpp"
\ No newline at end of file
diff --git a/include/queryosity/query_booker.h b/include/queryosity/query_booker.hpp
similarity index 99%
rename from include/queryosity/query_booker.h
rename to include/queryosity/query_booker.hpp
index 61d196cc..dde9d99a 100644
--- a/include/queryosity/query_booker.h
+++ b/include/queryosity/query_booker.hpp
@@ -5,7 +5,7 @@
 #include <utility>
 #include <vector>
 
-#include "query.h"
+#include "query.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/query_calculation.h b/include/queryosity/query_calculation.hpp
similarity index 94%
rename from include/queryosity/query_calculation.h
rename to include/queryosity/query_calculation.hpp
index 76d28403..770ff5e2 100644
--- a/include/queryosity/query_calculation.h
+++ b/include/queryosity/query_calculation.hpp
@@ -1,7 +1,7 @@
 #pragma once
 
-#include "query.h"
-#include "query_fillable.h"
+#include "query.hpp"
+#include "query_fillable.hpp"
 
 #include <vector>
 
diff --git a/include/queryosity/query_definition.h b/include/queryosity/query_definition.hpp
similarity index 93%
rename from include/queryosity/query_definition.h
rename to include/queryosity/query_definition.hpp
index cac2f522..fe318851 100644
--- a/include/queryosity/query_definition.h
+++ b/include/queryosity/query_definition.hpp
@@ -1,8 +1,8 @@
 #pragma once
 
-#include "query.h"
-#include "query_aggregation.h"
-#include "query_fillable.h"
+#include "query.hpp"
+#include "query_aggregation.hpp"
+#include "query_fillable.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/query_experiment.h b/include/queryosity/query_experiment.hpp
similarity index 94%
rename from include/queryosity/query_experiment.h
rename to include/queryosity/query_experiment.hpp
index 7989167d..e3325ff6 100644
--- a/include/queryosity/query_experiment.h
+++ b/include/queryosity/query_experiment.hpp
@@ -3,10 +3,10 @@
 #include <memory>
 #include <vector>
 
-#include "selection_cutflow.h"
+#include "selection_cutflow.hpp"
 
-#include "query.h"
-#include "query_booker.h"
+#include "query.hpp"
+#include "query_booker.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/query_fillable.h b/include/queryosity/query_fillable.hpp
similarity index 97%
rename from include/queryosity/query_fillable.h
rename to include/queryosity/query_fillable.hpp
index d3538c3e..5961c466 100644
--- a/include/queryosity/query_fillable.h
+++ b/include/queryosity/query_fillable.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "query.h"
+#include "query.hpp"
 
 namespace queryosity {
 
@@ -48,7 +48,7 @@ class query::fillable {
 
 } // namespace queryosity
 
-#include "column.h"
+#include "column.hpp"
 
 template <typename... Ins>
 template <typename... Vals>
diff --git a/include/queryosity/query_output.h b/include/queryosity/query_output.hpp
similarity index 95%
rename from include/queryosity/query_output.h
rename to include/queryosity/query_output.hpp
index a07e034b..d37d3aee 100644
--- a/include/queryosity/query_output.h
+++ b/include/queryosity/query_output.hpp
@@ -4,7 +4,7 @@
 #include <memory>
 #include <tuple>
 
-#include "query.h"
+#include "query.hpp"
 
 namespace queryosity {
 
@@ -39,7 +39,7 @@ template <typename Qry> struct output {
 
 } // namespace queryosity
 
-#include "dataflow.h"
+#include "dataflow.hpp"
 
 template <typename Qry>
 template <typename... Args>
diff --git a/include/queryosity/query_series.h b/include/queryosity/query_series.hpp
similarity index 98%
rename from include/queryosity/query_series.h
rename to include/queryosity/query_series.hpp
index 569f320d..a2273c65 100644
--- a/include/queryosity/query_series.h
+++ b/include/queryosity/query_series.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "query_definition.h"
+#include "query_definition.hpp"
 
 #include <vector>
 
diff --git a/include/queryosity/selection.h b/include/queryosity/selection.hpp
similarity index 96%
rename from include/queryosity/selection.h
rename to include/queryosity/selection.hpp
index a7a89a66..2c8e25bb 100644
--- a/include/queryosity/selection.h
+++ b/include/queryosity/selection.hpp
@@ -4,8 +4,8 @@
 #include <string>
 #include <vector>
 
-#include "action.h"
-#include "column.h"
+#include "action.hpp"
+#include "column.hpp"
 
 namespace queryosity {
 
@@ -66,8 +66,8 @@ template <typename T>
 constexpr bool is_selection_v = std::is_base_of_v<selection::node, T>;
 } // namespace queryosity
 
-#include "column_equation.h"
-#include "query.h"
+#include "column_equation.hpp"
+#include "query.hpp"
 
 inline queryosity::selection::node::node(const selection::node *presel,
                                          column::variable<double> dec)
diff --git a/include/queryosity/selection_applicator.h b/include/queryosity/selection_applicator.hpp
similarity index 97%
rename from include/queryosity/selection_applicator.h
rename to include/queryosity/selection_applicator.hpp
index 42430347..91e5c999 100644
--- a/include/queryosity/selection_applicator.h
+++ b/include/queryosity/selection_applicator.hpp
@@ -4,7 +4,7 @@
 #include <memory>
 #include <type_traits>
 
-#include "column_evaluator.h"
+#include "column_evaluator.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/selection_cut.h b/include/queryosity/selection_cut.hpp
similarity index 97%
rename from include/queryosity/selection_cut.h
rename to include/queryosity/selection_cut.hpp
index 6b84175c..937ae6d8 100644
--- a/include/queryosity/selection_cut.h
+++ b/include/queryosity/selection_cut.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "selection.h"
+#include "selection.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/selection_cutflow.h b/include/queryosity/selection_cutflow.hpp
similarity index 92%
rename from include/queryosity/selection_cutflow.h
rename to include/queryosity/selection_cutflow.hpp
index e6f1715c..75e63fbe 100644
--- a/include/queryosity/selection_cutflow.h
+++ b/include/queryosity/selection_cutflow.hpp
@@ -4,9 +4,9 @@
 #include <string>
 #include <vector>
 
-#include "column_computation.h"
-#include "selection.h"
-#include "selection_applicator.h"
+#include "column_computation.hpp"
+#include "selection.hpp"
+#include "selection_applicator.hpp"
 
 namespace queryosity {
 
@@ -40,9 +40,9 @@ class selection::cutflow : public column::computation {
 
 } // namespace queryosity
 
-#include "column.h"
-#include "selection_cut.h"
-#include "selection_weight.h"
+#include "column.hpp"
+#include "selection_cut.hpp"
+#include "selection_weight.hpp"
 
 template <typename Sel, typename Val>
 auto queryosity::selection::cutflow::apply(selection::node const *prev,
diff --git a/include/queryosity/selection_weight.h b/include/queryosity/selection_weight.hpp
similarity index 97%
rename from include/queryosity/selection_weight.h
rename to include/queryosity/selection_weight.hpp
index 84c5e794..210dd14c 100644
--- a/include/queryosity/selection_weight.h
+++ b/include/queryosity/selection_weight.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "selection.h"
+#include "selection.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/selection_yield.h b/include/queryosity/selection_yield.hpp
similarity index 95%
rename from include/queryosity/selection_yield.h
rename to include/queryosity/selection_yield.hpp
index 8258d22f..ac593459 100644
--- a/include/queryosity/selection_yield.h
+++ b/include/queryosity/selection_yield.hpp
@@ -1,9 +1,9 @@
 #pragma once
 
-#include "column.h"
-#include "dataflow.h"
-#include "query_output.h"
-#include "selection.h"
+#include "column.hpp"
+#include "dataflow.hpp"
+#include "query_output.hpp"
+#include "selection.hpp"
 
 #include <cmath>
 
diff --git a/include/queryosity/systematic.h b/include/queryosity/systematic.hpp
similarity index 100%
rename from include/queryosity/systematic.h
rename to include/queryosity/systematic.hpp
diff --git a/include/queryosity/systematic_resolver.h b/include/queryosity/systematic_resolver.hpp
similarity index 96%
rename from include/queryosity/systematic_resolver.h
rename to include/queryosity/systematic_resolver.hpp
index d88e3463..88bb5497 100644
--- a/include/queryosity/systematic_resolver.h
+++ b/include/queryosity/systematic_resolver.hpp
@@ -4,7 +4,7 @@
 #include <string>
 #include <type_traits>
 
-#include "systematic.h"
+#include "systematic.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/todo.h b/include/queryosity/todo.hpp
similarity index 98%
rename from include/queryosity/todo.h
rename to include/queryosity/todo.hpp
index 982c514d..cb369c3c 100644
--- a/include/queryosity/todo.h
+++ b/include/queryosity/todo.hpp
@@ -1,11 +1,11 @@
 #pragma once
 
-#include "dataflow.h"
-#include "detail.h"
-#include "lazy.h"
-#include "lazy_varied.h"
-#include "systematic.h"
-#include "systematic_resolver.h"
+#include "dataflow.hpp"
+#include "detail.hpp"
+#include "lazy.hpp"
+#include "lazy_varied.hpp"
+#include "systematic.hpp"
+#include "systematic_resolver.hpp"
 
 namespace queryosity {
 
diff --git a/include/queryosity/todo_varied.h b/include/queryosity/todo_varied.hpp
similarity index 99%
rename from include/queryosity/todo_varied.h
rename to include/queryosity/todo_varied.hpp
index d8e90fcd..244251c8 100644
--- a/include/queryosity/todo_varied.h
+++ b/include/queryosity/todo_varied.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "todo.h"
+#include "todo.hpp"
 
 namespace queryosity {
 
@@ -91,9 +91,9 @@ class varied<todo<Helper>> : public dataflow::node,
 
 } // namespace queryosity
 
-#include "dataflow.h"
-#include "lazy.h"
-#include "selection.h"
+#include "dataflow.hpp"
+#include "lazy.hpp"
+#include "selection.hpp"
 
 template <typename Helper>
 queryosity::varied<queryosity::todo<Helper>>::varied(
diff --git a/tests/test-01.cxx b/tests/test-01.cxx
index e0ecac57..08f85434 100644
--- a/tests/test-01.cxx
+++ b/tests/test-01.cxx
@@ -1,10 +1,10 @@
 #define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
 #include "doctest.h"
 
-#include "queryosity/json.h"
+#include <queryosity/json.hpp>
 #include <nlohmann/json.hpp>
 
-#include "queryosity.h"
+#include <queryosity.hpp>
 
 #include <random>
 #include <unordered_map>
diff --git a/tests/test-02.cxx b/tests/test-02.cxx
index a2e332ef..c41517e5 100644
--- a/tests/test-02.cxx
+++ b/tests/test-02.cxx
@@ -1,9 +1,9 @@
-#include "queryosity/json.h"
+#include <queryosity/json.hpp>
 #include <nlohmann/json.hpp>
 
 using json = qty::json;
 
-#include "queryosity.h"
+#include <queryosity.hpp>
 
 using dataflow = qty::dataflow;
 namespace multithread = qty::multithread;
diff --git a/tests/test-03.cxx b/tests/test-03.cxx
index 0361dbd3..5271643d 100644
--- a/tests/test-03.cxx
+++ b/tests/test-03.cxx
@@ -5,10 +5,10 @@
 #include <random>
 #include <unordered_map>
 
-#include "queryosity.h"
+#include <queryosity.hpp>
 
-#include "queryosity/json.h"
-#include "queryosity/wsum.h"
+#include <queryosity/json.hpp>
+#include <queryosity/wsum.hpp>
 
 using dataflow = qty::dataflow;
 namespace multithread = qty::multithread;
diff --git a/tests/test-04.cxx b/tests/test-04.cxx
index 28cdf74f..3186059c 100644
--- a/tests/test-04.cxx
+++ b/tests/test-04.cxx
@@ -5,10 +5,10 @@
 #include <random>
 #include <unordered_map>
 
-#include "queryosity.h"
+#include <queryosity.hpp>
 
-#include "queryosity/json.h"
-#include "queryosity/wsum.h"
+#include <queryosity/json.hpp>
+#include <queryosity/wsum.hpp>
 
 using dataflow = qty::dataflow;
 namespace multithread = qty::multithread;