diff --git a/src/regexp.c b/src/regexp.c
index 9c576c6..edd1293 100644
--- a/src/regexp.c
+++ b/src/regexp.c
@@ -2051,7 +2051,8 @@
 	// "flags & REGSUB_COPY" != 0.
 	if (copy)
 	{
-	    if (eval_result[nested] != NULL)
+	    if (eval_result[nested] != NULL &&
+		    STRLEN(eval_result[nested]) < destlen)
 	    {
 		STRCPY(dest, eval_result[nested]);
 		dst += STRLEN(eval_result[nested]);