diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 4d22dc8f2..f4ece4669 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -32,7 +32,7 @@ endif()
 
 # On MSVC remove /W3, as we are replacing it with /W4
 if(MSVC)
-    string(REPLACE "/W3" "" CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS})
+    string(REPLACE "/W3" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
 endif()
 
 # Emscripten needs special flag to use WebGL 2