diff --git a/README.md b/README.md
index 2f763e09..ccf98bd4 100644
--- a/README.md
+++ b/README.md
@@ -59,11 +59,14 @@ GLOBAL OPTIONS:
    --force-non-ssl, -f         force allow use of non-ssl
    --username value, -u value  username for the registry
    --password value, -p value  password for the registry
-   --registry value, -r value  URL to the private registry (ex. r.j3ss.co) (default: "https://registry-1.docker.io")
+   --registry value, -r value  URL to the private registry (ex. r.j3ss.co) (default: "https://registry-1.docker.io") [$REG_REGISTRY]
    --help, -h                  show help
    --version, -v               print the version
 ```
 
+Note that the `--registry` can be set by an environment variable `REG_REGISTRY`, so you can set this in your shell login scripts.
+Specifying the registry on the command-line will override an environment variable setting.
+
 ## Auth
 
 `reg` will automatically try to parse your docker config credentials, but if
diff --git a/main.go b/main.go
index 1110a740..6303dd86 100644
--- a/main.go
+++ b/main.go
@@ -48,9 +48,10 @@ func main() {
 			Usage: "password for the registry",
 		},
 		cli.StringFlag{
-			Name:  "registry, r",
-			Usage: "URL to the private registry (ex. r.j3ss.co)",
-			Value: repoutils.DefaultDockerRegistry,
+			Name:   "registry, r",
+			Usage:  "URL to the private registry (ex. r.j3ss.co)",
+			Value:  repoutils.DefaultDockerRegistry,
+			EnvVar: "REG_REGISTRY",
 		},
 	}