diff --git a/CMakeLists.txt b/CMakeLists.txt
index fbc222d5c..28eefe3b6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -69,7 +69,7 @@ IF (MSVC)
 
    # Precompiled headers
 ELSE ()
-	SET(CMAKE_C_FLAGS "-O2 -g -D_GNU_SOURCE -Wall -Wextra -Wno-missing-field-initializers -Wstrict-aliasing=2 -Wstrict-prototypes -Wmissing-prototypes ${CMAKE_C_FLAGS}")
+	SET(CMAKE_C_FLAGS "-O2 -g -D_GNU_SOURCE -fvisibility=hidden -Wall -Wextra -Wno-missing-field-initializers -Wstrict-aliasing=2 -Wstrict-prototypes -Wmissing-prototypes ${CMAKE_C_FLAGS}")
 	SET(CMAKE_C_FLAGS_DEBUG "-O0 -g")
 	IF (NOT MINGW) # MinGW always does PIC and complains if we tell it to
 		SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIC")