diff --git a/src/libregexp/test.c b/src/libregexp/test.c
new file mode 100644
index 0000000..83533ee
--- /dev/null
+++ b/src/libregexp/test.c
@@ -0,0 +1,46 @@
+#include "lib9.h"
+#include <regexp9.h>
+
+struct x
+{
+	char *re;
+	char *s;
+	Reprog *p;
+};
+
+struct x t[] = {
+	{ "^[^!@]+$", "/bin/upas/aliasmail '&'", 0 },
+	{ "^local!(.*)$", "/mail/box/\\1/mbox", 0 },
+	{ "^plan9!(.*)$", "\\1", 0 },
+	{ "^helix!(.*)$", "\\1", 0 },
+	{ "^([^!]+)@([^!@]+)$", "\\2!\\1", 0 },
+	{ "^(uk\\.[^!]*)(!.*)$", "/bin/upas/uk2uk '\\1' '\\2'", 0 },
+	{ "^[^!]*\\.[^!]*!.*$", "inet!&", 0 },
+	{ "^\xE2\x98\xBA$", "smiley", 0 },
+	{ "^(coma|research|pipe|pyxis|inet|hunny|gauss)!(.*)$", "/mail/lib/qmail '\\s' 'net!\\1' '\\2'", 0 },
+	{ "^.*$", "/mail/lib/qmail '\\s' 'net!research' '&'", 0 },
+	{ 0, 0, 0 },
+};
+
+main(int ac, char **av)
+{
+	Resub rs[10];
+	char dst[128];
+	int n;
+	struct x *tp;
+
+	for(tp = t; tp->re; tp++)
+		tp->p = regcomp(tp->re);
+
+
+	for(tp = t; tp->re; tp++){
+		print("%s VIA %s", av[1], tp->re);
+		memset(rs, 0, sizeof rs);
+		if(regexec(tp->p, av[1], rs, 10)){
+			regsub(tp->s, dst, sizeof dst, rs, 10);
+			print(" sub %s -> %s", tp->s, dst);
+		}
+		print("\n");
+	}
+	exit(0);
+}