diff --git a/src/regexp.h b/src/regexp.h
index c2a15b0..304c82d 100644
--- a/src/regexp.h
+++ b/src/regexp.h
@@ -177,4 +177,9 @@
     //char_u	*expr;
 };
 
+// Flags used by vim_regsub() and vim_regsub_both()
+#define REGSUB_COPY	    1
+#define REGSUB_MAGIC	    2
+#define REGSUB_BACKSLASH    4
+
 #endif	// _REGEXP_H