diff --git a/lib/ronin/core/output_formats.rb b/lib/ronin/core/output_formats.rb
index 4ba37e6..52f5700 100644
--- a/lib/ronin/core/output_formats.rb
+++ b/lib/ronin/core/output_formats.rb
@@ -65,9 +65,9 @@ def file_exts
         #
         # Registers a new output format.
         #
-        def register(name,ext,output_format)
+        def register(name,ext=nil,output_format)
           formats[name]  = output_format
-          file_exts[ext] = output_format
+          file_exts[ext] = output_format if ext
         end
 
         #
diff --git a/spec/output_formats_spec.rb b/spec/output_formats_spec.rb
index f5ca5a4..1aaf623 100644
--- a/spec/output_formats_spec.rb
+++ b/spec/output_formats_spec.rb
@@ -15,6 +15,14 @@ module OutputFormats
       register :json, '.json', JSON
       register :ndjson, '.ndjson', NDJSON
     end
+
+    class NoExtOutputFormat < Ronin::Core::OutputFormats::OutputFile; end
+
+    module NoExtOutputFormats
+      include Ronin::Core::OutputFormats
+
+      register :no_ext, NoExtOutputFormat
+    end
   end
 
   subject { TestOutputFormats::EmptyOutputFormats }
@@ -66,6 +74,14 @@ module OutputFormats
           )
         end
       end
+
+      context "when output formats without extension have been registered" do
+        subject { TestOutputFormats::NoExtOutputFormats }
+
+        it "must return an empty Hash" do
+          expect(subject.file_exts).to eq({})
+        end
+      end
     end
 
     describe ".register" do
@@ -78,6 +94,18 @@ module OutputFormats
       it "must register the output format in #file_exts with the given ext" do
         expect(subject.file_exts['.txt']).to be(described_class::TXT)
       end
+
+      context "without file extension" do
+        subject { TestOutputFormats::NoExtOutputFormats }
+
+        it "must register the output format in #formats with the given name" do
+          expect(subject.formats[:no_ext]).to be(TestOutputFormats::NoExtOutputFormat)
+        end
+
+        it "must not register the output format in #file_exts" do
+          expect(subject.file_exts).to eq({})
+        end
+      end
     end
 
     describe ".infer_from" do