diff --git a/mongo/mongo_test.go b/mongo/mongo_test.go
index af12e3d50cf..93f69e7aed8 100644
--- a/mongo/mongo_test.go
+++ b/mongo/mongo_test.go
@@ -138,11 +138,11 @@ func (s *MongoSuite) assertMongoConfigFile(c *gc.C, dataDir string, ipV6 bool) {
 	c.Assert(err, jc.ErrorIsNil)
 	part1 := fmt.Sprintf(`
 # WARNING
-# autogenerated by juju on %s
+# autogenerated by juju on .*
 # manual changes to this file are likely to be overwritten
 auth = true
 bind_ip_all = true
-dbpath = %s/db`[1:], s.clock.Now().UTC().Format(time.RFC822), dataDir)
+dbpath = %s/db`[1:], dataDir)
 	if ipV6 {
 		part1 += "\nipv6 = true"
 	}
@@ -161,7 +161,7 @@ tlsCertificateKeyFile = %s/server.pem
 tlsCertificateKeyFilePassword=ignored
 tlsMode = requireTLS`, dataDir, dataDir, dataDir)
 
-	c.Assert(string(contents), jc.DeepEquals, part1+part2)
+	c.Assert(string(contents), gc.Matches, part1+part2)
 }
 
 func (s *MongoSuite) TestEnsureServerInstalled(c *gc.C) {