diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0d7be89a..67bb748b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -28,8 +28,8 @@ endif()
 
 if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
   set(C_CXX_FLAGS "-Wall -Werror -Wformat=2 -Wsign-compare -Wmissing-field-initializers -ggdb -fvisibility=hidden")
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${C_CXX_FLAGS}")
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++0x ${C_CXX_FLAGS}")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${C_CXX_FLAGS} -Wmissing-prototypes")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++0x ${C_CXX_FLAGS} -Wmissing-declarations")
 elseif(MSVC)
   set(MSVC_DISABLED_WARNINGS_LIST
       "C4100" # 'exarg' : unreferenced formal parameter