diff --git a/config/config_test.go b/config/config_test.go
index ae5c010fc9..905792a258 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -695,6 +695,9 @@ var expectedErrors = []struct {
 	}, {
 		filename: "marathon_authtoken_bearertoken.bad.yml",
 		errMsg:   "marathon_sd: at most one of bearer_token, bearer_token_file, auth_token & auth_token_file must be configured",
+	}, {
+		filename: "openstack_role.bad.yml",
+		errMsg:   "unknown OpenStack SD role",
 	}, {
 		filename: "url_in_targetgroup.bad.yml",
 		errMsg:   "\"http://bad\" is not a valid hostname",
diff --git a/config/testdata/openstack_role.bad.yml b/config/testdata/openstack_role.bad.yml
new file mode 100644
index 0000000000..6c607d8c6d
--- /dev/null
+++ b/config/testdata/openstack_role.bad.yml
@@ -0,0 +1,4 @@
+scrape_configs:
+- openstack_sd_configs:
+  - role: invalid
+
diff --git a/discovery/openstack/openstack.go b/discovery/openstack/openstack.go
index 0103edbf08..8133302811 100644
--- a/discovery/openstack/openstack.go
+++ b/discovery/openstack/openstack.go
@@ -84,7 +84,7 @@ func (c *Role) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	case OpenStackRoleHypervisor, OpenStackRoleInstance:
 		return nil
 	default:
-		return fmt.Errorf("Unknown OpenStack SD role %q", *c)
+		return fmt.Errorf("unknown OpenStack SD role %q", *c)
 	}
 }