diff --git a/docker_custodian/docker_autostop.py b/docker_custodian/docker_autostop.py
index 021f60e..780ff40 100644
--- a/docker_custodian/docker_autostop.py
+++ b/docker_custodian/docker_autostop.py
@@ -95,6 +95,10 @@ def get_opts(args=None):
     )
     opts = parser.parse_args(args=args)
 
+    if len(sys.argv) < 2:
+        parser.print_help()
+        exit(0)
+
     if not opts.prefix:
         parser.error("Running with no --prefix will match nothing.")
 
diff --git a/docker_custodian/docker_gc.py b/docker_custodian/docker_gc.py
index db7aba9..40dae8d 100644
--- a/docker_custodian/docker_gc.py
+++ b/docker_custodian/docker_gc.py
@@ -269,6 +269,10 @@ def get_args(args=None):
         help="Path to a file which contains a list of images to exclude, one "
              "image tag per line.")
 
+    if len(sys.argv) < 2:
+        parser.print_help()
+        exit(0)
+
     return parser.parse_args(args=args)