diff --git a/source/lib/lib_api.h b/source/lib/lib_api.h
index 91c9e3cace..8ca3ddccf9 100644
--- a/source/lib/lib_api.h
+++ b/source/lib/lib_api.h
@@ -24,6 +24,6 @@
 #   define LIB_API
 #  endif
 # else
-#  error Don't know how to define LIB_API for this compiler
+#  error "Don't know how to define LIB_API for this compiler"
 # endif
 #endif