diff --git a/4cpp_lexer.h b/4cpp_lexer.h
index 6e8f48ae..7409dfec 100644
--- a/4cpp_lexer.h
+++ b/4cpp_lexer.h
@@ -17,8 +17,8 @@
 #include <stdint.h>
 #if !defined(FSTRING_GUARD)
 # define FSTRING_IMPLEMENTATION
+# include "4coder_string.h"
 #endif
-#include "4coder_string.h"
 #include "4cpp_lexer_types.h"
 #include "4cpp_lexer_tables.c"