diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index be49817a38..91825ec9a0 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -80,8 +80,6 @@ endif()
 
 if(ENABLE_UNICODE AND MINGW)
   target_link_libraries(${EXE_NAME} -municode)
-  # GCC doesn't know about wmain
-  set_source_files_properties(tool_main.c PROPERTIES COMPILE_FLAGS "-Wno-missing-prototypes -Wno-missing-declarations")
 endif()
 
 source_group("curlX source files" FILES ${CURLX_CFILES})
diff --git a/src/tool_main.c b/src/tool_main.c
index de7276f14f..62c4a597e5 100644
--- a/src/tool_main.c
+++ b/src/tool_main.c
@@ -236,6 +236,11 @@ static void main_free(struct GlobalConfig *config)
 ** curl tool main function.
 */
 #ifdef _UNICODE
+#if defined(__GNUC__)
+/* GCC doesn't know about wmain() */
+#pragma GCC diagnostic ignored "-Wmissing-prototypes"
+#pragma GCC diagnostic ignored "-Wmissing-declarations"
+#endif
 int wmain(int argc, wchar_t *argv[])
 #else
 int main(int argc, char *argv[])