diff --git a/Modules/FindThreads.cmake b/Modules/FindThreads.cmake
index ee498670ff..e3e6591a36 100644
--- a/Modules/FindThreads.cmake
+++ b/Modules/FindThreads.cmake
@@ -66,7 +66,7 @@ endif()
 set(PTHREAD_C_CXX_TEST_SOURCE [====[
 #include <pthread.h>
 
-void* test_func(void* data)
+static void* test_func(void* data)
 {
   return data;
 }