diff --git a/cmake/protobuf-module.cmake.in b/cmake/protobuf-module.cmake.in
index 0bb05e38fa..6a6ae1260a 100644
--- a/cmake/protobuf-module.cmake.in
+++ b/cmake/protobuf-module.cmake.in
@@ -184,6 +184,8 @@ foreach(Camel
     Protobuf_LITE_LIBRARY
     Protobuf_LITE_LIBRARY_DEBUG
     )
-    string(TOUPPER ${Camel} UPPER)
-    set(${UPPER} ${${Camel}})
+    if(DEFINED ${Camel})
+        string(TOUPPER ${Camel} UPPER)
+        set(${UPPER} ${${Camel}})
+    endif()
 endforeach()