diff --git a/cmake/debug_flags.cmake b/cmake/debug_flags.cmake
index 976b611..0009039 100644
--- a/cmake/debug_flags.cmake
+++ b/cmake/debug_flags.cmake
@@ -15,7 +15,7 @@ if(CMAKE_CXX_COMPILER_ID MATCHES "GNU" OR CMAKE_CXX_COMPILER_ID MATCHES "Clang"
     "-Wsign-conversion"
     "-Wold-style-cast"
     "-Wzero-as-null-pointer-constant"
-    # "-Wmissing-declarations"
+    "-Wmissing-declarations"
     "-Wcast-align"
     "-Wunused"
     "-Woverloaded-virtual"