diff --git a/app.yaml b/app.yaml
index 51946a9..f30d7aa 100644
--- a/app.yaml
+++ b/app.yaml
@@ -1,6 +1,4 @@
-runtime: go
-api_version: go1
-
+runtime: go125
 handlers:
 - url: /.*
-  script: _go_app
+  script: auto
diff --git a/appengine.go b/appengine.go
deleted file mode 100644
index 6cb4098..0000000
--- a/appengine.go
+++ /dev/null
@@ -1,42 +0,0 @@
-// Copyright 2017 Google Inc. All Rights Reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-//+build appengine
-
-package main
-
-import (
-	"io/ioutil"
-	"log"
-	"net/http"
-
-	"google.golang.org/appengine"
-)
-
-func main() {
-	vanity, err := ioutil.ReadFile("./vanity.yaml")
-	if err != nil {
-		log.Fatal(err)
-	}
-	h, err := newHandler(vanity)
-	if err != nil {
-		log.Fatal(err)
-	}
-	http.Handle("/", h)
-	appengine.Main()
-}
-
-func defaultHost(r *http.Request) string {
-	return appengine.DefaultVersionHostname(appengine.NewContext(r))
-}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..8fca8d4
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,5 @@
+module github.com/thisissoon/govanityurls
+
+go 1.12
+
+require gopkg.in/yaml.v2 v2.2.2
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..bd555a3
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,3 @@
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
diff --git a/handler.go b/handler.go
index 8b7738d..d2064a9 100644
--- a/handler.go
+++ b/handler.go
@@ -68,10 +68,12 @@ func newHandler(config []byte) (*handler, error) {
 			display: e.Display,
 			vcs:     e.VCS,
 		}
+		isGithub := strings.HasPrefix(e.Repo, "https://github.com/")
+		isGitlab := strings.HasPrefix(e.Repo, "https://gitlab.com/")
 		switch {
 		case e.Display != "":
 			// Already filled in.
-		case strings.HasPrefix(e.Repo, "https://github.com/"):
+		case isGithub, isGitlab:
 			pc.display = fmt.Sprintf("%v %v/tree/master{/dir} %v/blob/master{/dir}/{file}#L{line}", e.Repo, e.Repo, e.Repo)
 		case strings.HasPrefix(e.Repo, "https://bitbucket.org"):
 			pc.display = fmt.Sprintf("%v %v/src/default{/dir} %v/src/default{/dir}/{file}#{file}-{line}", e.Repo, e.Repo, e.Repo)
@@ -82,7 +84,7 @@ func newHandler(config []byte) (*handler, error) {
 			if e.VCS != "bzr" && e.VCS != "git" && e.VCS != "hg" && e.VCS != "svn" {
 				return nil, fmt.Errorf("configuration for %v: unknown VCS %s", path, e.VCS)
 			}
-		case strings.HasPrefix(e.Repo, "https://github.com/"):
+		case isGithub, isGitlab:
 			pc.vcs = "git"
 		default:
 			return nil, fmt.Errorf("configuration for %v: cannot infer VCS from %s", path, e.Repo)
diff --git a/handler_test.go b/handler_test.go
index b3e9a69..64e2171 100644
--- a/handler_test.go
+++ b/handler_test.go
@@ -64,6 +64,16 @@ func TestHandler(t *testing.T) {
 			goImport: "example.com/gopdf hg https://bitbucket.org/zombiezen/gopdf",
 			goSource: "example.com/gopdf https://bitbucket.org/zombiezen/gopdf https://bitbucket.org/zombiezen/gopdf/src/default{/dir} https://bitbucket.org/zombiezen/gopdf/src/default{/dir}/{file}#{file}-{line}",
 		},
+		{
+			name: "display Gitlab inference",
+			config: "host: example.com\n" +
+				"paths:\n" +
+				"  /portmidi:\n" +
+				"    repo: https://gitlab.com/rakyll/portmidi\n",
+			path:     "/portmidi",
+			goImport: "example.com/portmidi git https://gitlab.com/rakyll/portmidi",
+			goSource: "example.com/portmidi https://gitlab.com/rakyll/portmidi https://gitlab.com/rakyll/portmidi/tree/master{/dir} https://gitlab.com/rakyll/portmidi/blob/master{/dir}/{file}#L{line}",
+		},
 		{
 			name: "Bitbucket Git",
 			config: "host: example.com\n" +
@@ -237,10 +247,10 @@ func TestPathConfigSetFind(t *testing.T) {
 			want:  "/y",
 		},
 		{
-			paths: []string{"/example/helloworld", "/", "/y", "/foo"},
-			query: "/x/y/",
-			want:  "/",
-			subpath:  "x/y/",
+			paths:   []string{"/example/helloworld", "/", "/y", "/foo"},
+			query:   "/x/y/",
+			want:    "/",
+			subpath: "x/y/",
 		},
 		{
 			paths: []string{"/example/helloworld", "/y", "/foo"},
diff --git a/main.go b/main.go
index 6d06a81..3b6fab7 100644
--- a/main.go
+++ b/main.go
@@ -12,11 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//+build !appengine
-
 package main
 
 import (
+	"fmt"
 	"io/ioutil"
 	"log"
 	"net/http"
@@ -42,7 +41,13 @@ func main() {
 		log.Fatal(err)
 	}
 	http.Handle("/", h)
-	if err := http.ListenAndServe(":8080", nil); err != nil {
+
+	port := os.Getenv("PORT")
+	if port == "" {
+		port = "8080"
+		log.Printf("Defaulting to port %s", port)
+	}
+	if err := http.ListenAndServe(fmt.Sprintf(":%s", port), nil); err != nil {
 		log.Fatal(err)
 	}
 }