--- a/Source/GmmLib/CMakeLists.txt
+++ b/Source/GmmLib/CMakeLists.txt
@@ -40,7 +40,7 @@
 endif()
 
 if(NOT DEFINED GMMLIB_API_PATCH_VERSION)
-    set(GMMLIB_API_PATCH_VERSION PATCH_VERSION)
+    set(GMMLIB_API_PATCH_VERSION "${PATCH_VERSION}")
 endif()
 
 message(STATUS "API version: ${GMMLIB_API_MAJOR_VERSION}.${GMMLIB_API_MINOR_VERSION}.${GMMLIB_API_PATCH_VERSION}")