diff --git a/.gitignore b/.gitignore
index 56abde5..5022fb8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,3 @@
 /data/
 /custom.html
-/vendor/*
-!/vendor/vendor.json
+/vendor/
diff --git a/.travis.yml b/.travis.yml
index 80f2a92..32090e7 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,6 +5,11 @@ language: go
 go:
   - stable
 
+# Go module behaviour is disabled by default for packages inside GOPATH.
+# Turn module support on explicitly:
+env:
+  - GO111MODULE=on
+
 deploy:
   provider: heroku
   app: ifconfig-co
diff --git a/Makefile b/Makefile
index 60a2441..d840170 100644
--- a/Makefile
+++ b/Makefile
@@ -23,12 +23,12 @@ ifdef TRAVIS
 endif
 
 check-fmt:
-	bash -c 'diff --line-format="%L" <(echo -n) <(gofmt -d -s $$(find . -type f -name "*.go" -not -path "./vendor/*"))'
+	bash -c "diff --line-format='%L' <(echo -n) <(gofmt -d -s .)"
 
 lint: check-fmt vet megacheck
 
 deps:
-	go get -d -v ./...
+	go get
 
 install:
 	go install ./...
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..d6ab659
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,10 @@
+// +heroku install ./...
+// +heroku goVersion go1.11
+module github.com/mpolden/echoip
+
+require (
+	github.com/jessevdk/go-flags v1.4.0
+	github.com/oschwald/geoip2-golang v1.1.0
+	github.com/oschwald/maxminddb-golang v1.2.1
+	golang.org/x/sys v0.0.0-20180202135801-37707fdb30a5
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..1d32d93
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,4 @@
+github.com/jessevdk/go-flags v1.4.0/go.mod h1:4FA24M0QyGHXBuZZK/XkWh8h0e1EYbRYJSGM75WSRxI=
+github.com/oschwald/geoip2-golang v1.1.0/go.mod h1:0LTTzix/Ao1uMvOhAV4iLU0Lz7eCrP94qZWBTDKf0iE=
+github.com/oschwald/maxminddb-golang v1.2.1/go.mod h1:3jhIUymTJ5VREKyIhWm66LJiQt04F0UCDdodShpjWsY=
+golang.org/x/sys v0.0.0-20180202135801-37707fdb30a5/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
diff --git a/vendor/vendor.json b/vendor/vendor.json
deleted file mode 100644
index 3da2c3b..0000000
--- a/vendor/vendor.json
+++ /dev/null
@@ -1,43 +0,0 @@
-{
-  "comment": "",
-  "ignore": "test",
-  "package": [
-    {
-      "checksumSHA1": "OH94abBdbmoVqyRqYBfgUT9N494=",
-      "path": "github.com/jessevdk/go-flags",
-      "revision": "1c38ed7ad0cc3d9e66649ac398c30e45f395c4eb",
-      "revisionTime": "2018-03-31T12:42:32Z"
-    },
-    {
-      "checksumSHA1": "um5Gw7FZwz/GoxIXVIlSL1NigXk=",
-      "path": "github.com/oschwald/geoip2-golang",
-      "revision": "5b1dc16861f81d05d9836bb21c2d0d65282fc0b8",
-      "revisionTime": "2017-04-23T21:58:58Z"
-    },
-    {
-      "checksumSHA1": "hRW1mYxnRGfMCm0g7DfkFMUAtpg=",
-      "path": "github.com/oschwald/maxminddb-golang",
-      "revision": "8727e98aa1b91610eb184ed1ab615943b8d9deb0",
-      "revisionTime": "2018-01-03T00:51:53Z"
-    },
-    {
-      "checksumSHA1": "osb18zDjd7/RMAMUuN3qP+w0ewE=",
-      "path": "golang.org/x/sys/unix",
-      "revision": "37707fdb30a5b38865cfb95e5aab41707daec7fd",
-      "revisionTime": "2018-02-02T13:35:31Z"
-    },
-    {
-      "checksumSHA1": "eQq+ZoTWPjyizS9XalhZwfGjQao=",
-      "path": "golang.org/x/sys/windows",
-      "revision": "37707fdb30a5b38865cfb95e5aab41707daec7fd",
-      "revisionTime": "2018-02-02T13:35:31Z"
-    }
-  ],
-  "rootPath": "github.com/mpolden/echoip",
-  "heroku": {
-    "install": [
-      "./..."
-    ],
-    "goVersion": "go1.10.3"
-  }
-}