diff --git a/sys/src/libregexp/regcomp.c b/sys/src/libregexp/regcomp.c
index 3e3ba6ae5..3bbc26ca9 100644
--- a/sys/src/libregexp/regcomp.c
+++ b/sys/src/libregexp/regcomp.c
@@ -299,7 +299,7 @@ compile(Renode *parsetr, Reprog *reprog, int nl)
 	sub = 0;
 	reinst = (Reinst*)(reprog+1);
 	end = compile1(parsetr, reinst, &sub, nl);
-	assert(reinst + reprog->len == end);
+	assert(end <= reinst + reprog->len);
 	return reinst;
 }