diff --git a/thirdparty/antiword/CMakeLists.txt b/thirdparty/antiword/CMakeLists.txt
index 5b27e75eb..972e2f95f 100644
--- a/thirdparty/antiword/CMakeLists.txt
+++ b/thirdparty/antiword/CMakeLists.txt
@@ -47,3 +47,4 @@ endif(WIN32)
 
 ADD_LIBRARY(antiword STATIC ${ANTIWORD_SOURCES})
 
+set_target_properties(antiword PROPERTIES C_VISIBILITY_PRESET hidden)
diff --git a/thirdparty/chmlib/CMakeLists.txt b/thirdparty/chmlib/CMakeLists.txt
index fce751000..5f2668d31 100644
--- a/thirdparty/chmlib/CMakeLists.txt
+++ b/thirdparty/chmlib/CMakeLists.txt
@@ -19,3 +19,4 @@ SET (CHMLIB_SOURCES
 
 ADD_LIBRARY(chmlib STATIC ${CHMLIB_SOURCES})
 
+set_target_properties(chmlib PROPERTIES C_VISIBILITY_PRESET hidden)