diff --git a/CHANGELOG.md b/CHANGELOG.md
index f461742cea..e3f66a113b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,8 @@ NEW FEATURES:
 * Wildcard ignore support. (#1156)
 * Disable SourceManager lock by setting `DEPNOLOCK` environment variable.
 (#1206)
+* `dep ensure -no-vendor -dry-run` now exits with an error when changes would
+have to be made to `Gopkg.lock`. This is useful for CI. (#1256)
 
 BUG FIXES:
 
diff --git a/cmd/dep/ensure.go b/cmd/dep/ensure.go
index 4b4c623052..63e4868ad7 100644
--- a/cmd/dep/ensure.go
+++ b/cmd/dep/ensure.go
@@ -110,6 +110,12 @@ dep ensure -update -no-vendor
 
     As above, but only modify Gopkg.lock; leave vendor/ unchanged.
 
+dep ensure -no-vendor -dry-run
+
+    This fails with a non zero exit code if Gopkg.lock is not up to date with
+    the Gopkg.toml or the project imports. It can be useful to run this during
+    CI to check if Gopkg.lock is up to date.
+
 `
 
 var (
@@ -267,6 +273,10 @@ func (cmd *ensureCommand) runDefault(ctx *dep.Ctx, args []string, p *dep.Project
 		return errors.WithMessage(sw.Write(p.AbsRoot, sm, true, logger), "grouped write of manifest, lock and vendor")
 	}
 
+	if cmd.noVendor && cmd.dryRun {
+		return errors.New("Gopkg.lock was not up to date")
+	}
+
 	solution, err := solver.Solve()
 	if err != nil {
 		handleAllTheFailuresOfTheWorld(err)
diff --git a/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/final/Gopkg.lock b/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/final/Gopkg.lock
new file mode 100644
index 0000000000..c7f497e7a1
--- /dev/null
+++ b/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/final/Gopkg.lock
@@ -0,0 +1,15 @@
+# This file is autogenerated, do not edit; changes may be undone by the next 'dep ensure'.
+
+
+[[projects]]
+  name = "github.com/sdboyer/deptest"
+  packages = ["."]
+  revision = "ff2948a2ac8f538c4ecd55962e919d1e13e74baf"
+  version = "v1.0.0"
+
+[solve-meta]
+  analyzer-name = "dep"
+  analyzer-version = 1
+  inputs-digest = "14b07b05e0f01051b03887ab2bf80b516bc5510ea92f75f76c894b1745d8850c"
+  solver-name = "gps-cdcl"
+  solver-version = 1
diff --git a/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/final/Gopkg.toml b/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/final/Gopkg.toml
new file mode 100644
index 0000000000..e242e02114
--- /dev/null
+++ b/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/final/Gopkg.toml
@@ -0,0 +1,4 @@
+
+[[constraint]]
+  name = "github.com/sdboyer/deptest"
+  version = "1.0.0"
diff --git a/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/initial/Gopkg.lock b/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/initial/Gopkg.lock
new file mode 100644
index 0000000000..c7f497e7a1
--- /dev/null
+++ b/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/initial/Gopkg.lock
@@ -0,0 +1,15 @@
+# This file is autogenerated, do not edit; changes may be undone by the next 'dep ensure'.
+
+
+[[projects]]
+  name = "github.com/sdboyer/deptest"
+  packages = ["."]
+  revision = "ff2948a2ac8f538c4ecd55962e919d1e13e74baf"
+  version = "v1.0.0"
+
+[solve-meta]
+  analyzer-name = "dep"
+  analyzer-version = 1
+  inputs-digest = "14b07b05e0f01051b03887ab2bf80b516bc5510ea92f75f76c894b1745d8850c"
+  solver-name = "gps-cdcl"
+  solver-version = 1
diff --git a/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/initial/Gopkg.toml b/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/initial/Gopkg.toml
new file mode 100644
index 0000000000..e242e02114
--- /dev/null
+++ b/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/initial/Gopkg.toml
@@ -0,0 +1,4 @@
+
+[[constraint]]
+  name = "github.com/sdboyer/deptest"
+  version = "1.0.0"
diff --git a/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/initial/main.go b/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/initial/main.go
new file mode 100644
index 0000000000..1fe0d19d6a
--- /dev/null
+++ b/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/initial/main.go
@@ -0,0 +1,12 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	_ "github.com/sdboyer/deptest"
+)
+
+func main() {
+}
diff --git a/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/testcase.json b/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/testcase.json
new file mode 100644
index 0000000000..f3bdbe7e90
--- /dev/null
+++ b/cmd/dep/testdata/harness_tests/ensure/default/hasheq-novendor-dry/testcase.json
@@ -0,0 +1,5 @@
+{
+  "commands": [
+    ["ensure", "-no-vendor", "-dry-run"]
+  ]
+}
diff --git a/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/final/Gopkg.lock b/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/final/Gopkg.lock
new file mode 100644
index 0000000000..11cb12c378
--- /dev/null
+++ b/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/final/Gopkg.lock
@@ -0,0 +1,16 @@
+# This file is autogenerated, do not edit; changes may be undone by the next 'dep ensure'.
+
+
+[[projects]]
+  name = "github.com/sdboyer/deptest"
+  packages = ["."]
+  revision = "ff2948a2ac8f538c4ecd55962e919d1e13e74baf"
+  version = "v1.0.0"
+
+[solve-meta]
+  analyzer-name = "dep"
+  analyzer-version = 1
+  # manually modified hash digest, it will not match any known inputs
+  inputs-digest = "94b07b05e0f01051b03887ab2bf80b516bc5510ea92f75f76c894b1745d8850c"
+  solver-name = "gps-cdcl"
+  solver-version = 1
diff --git a/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/final/Gopkg.toml b/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/final/Gopkg.toml
new file mode 100644
index 0000000000..e242e02114
--- /dev/null
+++ b/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/final/Gopkg.toml
@@ -0,0 +1,4 @@
+
+[[constraint]]
+  name = "github.com/sdboyer/deptest"
+  version = "1.0.0"
diff --git a/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/initial/Gopkg.lock b/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/initial/Gopkg.lock
new file mode 100644
index 0000000000..11cb12c378
--- /dev/null
+++ b/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/initial/Gopkg.lock
@@ -0,0 +1,16 @@
+# This file is autogenerated, do not edit; changes may be undone by the next 'dep ensure'.
+
+
+[[projects]]
+  name = "github.com/sdboyer/deptest"
+  packages = ["."]
+  revision = "ff2948a2ac8f538c4ecd55962e919d1e13e74baf"
+  version = "v1.0.0"
+
+[solve-meta]
+  analyzer-name = "dep"
+  analyzer-version = 1
+  # manually modified hash digest, it will not match any known inputs
+  inputs-digest = "94b07b05e0f01051b03887ab2bf80b516bc5510ea92f75f76c894b1745d8850c"
+  solver-name = "gps-cdcl"
+  solver-version = 1
diff --git a/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/initial/Gopkg.toml b/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/initial/Gopkg.toml
new file mode 100644
index 0000000000..e242e02114
--- /dev/null
+++ b/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/initial/Gopkg.toml
@@ -0,0 +1,4 @@
+
+[[constraint]]
+  name = "github.com/sdboyer/deptest"
+  version = "1.0.0"
diff --git a/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/initial/main.go b/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/initial/main.go
new file mode 100644
index 0000000000..1fe0d19d6a
--- /dev/null
+++ b/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/initial/main.go
@@ -0,0 +1,12 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	_ "github.com/sdboyer/deptest"
+)
+
+func main() {
+}
diff --git a/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/testcase.json b/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/testcase.json
new file mode 100644
index 0000000000..2e54069437
--- /dev/null
+++ b/cmd/dep/testdata/harness_tests/ensure/default/hashneq-novendor-dry/testcase.json
@@ -0,0 +1,6 @@
+{
+  "commands": [
+    ["ensure", "-no-vendor", "-dry-run"]
+  ],
+  "error-expected": "Gopkg.lock was not up to date"
+}