diff --git a/src/cmd/go/internal/modcmd/init.go b/src/cmd/go/internal/modcmd/init.go
index 0f7421e584..b94453bab0 100644
--- a/src/cmd/go/internal/modcmd/init.go
+++ b/src/cmd/go/internal/modcmd/init.go
@@ -35,6 +35,9 @@ func runInit(cmd *base.Command, args []string) {
 	if len(args) == 1 {
 		modload.CmdModModule = args[0]
 	}
+	if os.Getenv("GO111MODULE") == "off" {
+		base.Fatalf("go mod init: modules disabled by GO111MODULE=off; see 'go help modules'")
+	}
 	if _, err := os.Stat("go.mod"); err == nil {
 		base.Fatalf("go mod init: go.mod already exists")
 	}
diff --git a/src/cmd/go/testdata/script/mod_off_init.txt b/src/cmd/go/testdata/script/mod_off_init.txt
new file mode 100644
index 0000000000..f9a4e10bd4
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_off_init.txt
@@ -0,0 +1,7 @@
+env GO111MODULE=off
+
+# This script tests that running go mod init with
+# GO111MODULE=off when outside of GOPATH will fatal
+# with an error message.
+! go mod init
+stderr 'go mod init: modules disabled by GO111MODULE=off; see ''go help modules'''