Remove the `.Provider.` bit.
diff --git a/openstack/common/extensions/requests.go b/openstack/common/extensions/requests.go
index f1b9c22..3ca6e12 100755
--- a/openstack/common/extensions/requests.go
+++ b/openstack/common/extensions/requests.go
@@ -10,7 +10,7 @@
 func Get(c *gophercloud.ServiceClient, alias string) GetResult {
 	var res GetResult
 	_, res.Err = perigee.Request("GET", ExtensionURL(c, alias), perigee.Options{
-		MoreHeaders: c.Provider.AuthenticatedHeaders(),
+		MoreHeaders: c.AuthenticatedHeaders(),
 		Results:     &res.Body,
 		OkCodes:     []int{200},
 	})