diff --git a/cmake/sdlchecks.cmake b/cmake/sdlchecks.cmake
index 0e28df618..364cdb3cb 100644
--- a/cmake/sdlchecks.cmake
+++ b/cmake/sdlchecks.cmake
@@ -799,7 +799,7 @@ endmacro()
 # - PkgCheckModules
 macro(CheckEGL)
   pkg_check_modules(EGL egl)
-  string(REPLACE "-D_THREAD_SAFE;" "-D_THREAD_SAFE=1;" EGL_CFLAGS ${EGL_CFLAGS})
+  string(REPLACE "-D_THREAD_SAFE;" "-D_THREAD_SAFE=1;" EGL_CFLAGS "${EGL_CFLAGS}")
 endmacro()
 
 # Requires: