diff --git a/shipyard_client/cli/action.py b/shipyard_client/cli/action.py
index 4b24860e..6dde3865 100644
--- a/shipyard_client/cli/action.py
+++ b/shipyard_client/cli/action.py
@@ -167,10 +167,11 @@ class CliAction(AbstractCliAction):
             if self.auth_vars[var] is None:
                 err_txt.append(
                     'Missing the required authorization variable: '
-                    '--os_{}'.format(var))
+                    '--os-{}'.format(var.replace('_', '-')))
         if err_txt:
             for var in self.auth_vars:
                 if (self.auth_vars.get(var) is None and
                         var not in required_auth_vars):
-                    err_txt.append('- Also not set: --os_{}'.format(var))
+                    err_txt.append('- Also not set: --os-{}'.format(
+                        var.replace('_', '-')))
             raise AuthValuesError(diagnostic='\n'.join(err_txt))
diff --git a/shipyard_client/tests/unit/cli/test_auth_validations.py b/shipyard_client/tests/unit/cli/test_auth_validations.py
index 5a489ddc..ab8ab147 100644
--- a/shipyard_client/tests/unit/cli/test_auth_validations.py
+++ b/shipyard_client/tests/unit/cli/test_auth_validations.py
@@ -42,9 +42,9 @@ def test_validate_auth_vars_missing_required():
         try:
             action.validate_auth_vars()
         except AuthValuesError as ex:
-            assert 'os_auth_url' in ex.diagnostic
-            assert 'os_username' not in ex.diagnostic
-            assert 'os_password' not in ex.diagnostic
+            assert 'os-auth-url' in ex.diagnostic
+            assert 'os-username' not in ex.diagnostic
+            assert 'os-password' not in ex.diagnostic
             raise
 
 
@@ -63,7 +63,7 @@ def test_validate_auth_vars_missing_required_and_others():
         try:
             action.validate_auth_vars()
         except AuthValuesError as ex:
-            assert 'os_auth_url' in ex.diagnostic
-            assert 'os_username' in ex.diagnostic
-            assert 'os_password' not in ex.diagnostic
+            assert 'os-auth-url' in ex.diagnostic
+            assert 'os-username' in ex.diagnostic
+            assert 'os-password' not in ex.diagnostic
             raise