diff --git a/cpp/_macro.cpp b/cpp/_macro.cpp
index bffa78a..f7adcb4 100644
--- a/cpp/_macro.cpp
+++ b/cpp/_macro.cpp
@@ -1,12 +1,13 @@
 #ifndef __COMFORTABLE_SWIPE__macro_hpp__
 #define __COMFORTABLE_SWIPE__macro_hpp__
 
+#undef COMFORTABLE_SWIPE_CONFIG
 #ifndef COMFORTABLE_SWIPE_CONFIG
-#error "COMFORTABLE_SWIPE_CONFIG must be defined."
+#error COMFORTABLE_SWIPE_CONFIG must be defined.
 #endif /* COMFORTABLE_SWIPE_CONFIG */
 
 #ifndef COMFORTABLE_SWIPE_VERSION
-#warning "COMFORTABLE_SWIPE_VERSION is not defined."
+#warning COMFORTABLE_SWIPE_VERSION is not defined.
 #endif /* COMFORTABLE_SWIPE_VERSION */
 
 #endif /* __COMFORTABLE_SWIPE__macro_hpp__ */