more consistent naming
diff --git a/openstack/compute/v2/extensions/secgroups/results.go b/openstack/compute/v2/extensions/secgroups/results.go
index 5e18c0b..764f580 100644
--- a/openstack/compute/v2/extensions/secgroups/results.go
+++ b/openstack/compute/v2/extensions/secgroups/results.go
@@ -76,12 +76,11 @@
 }
 
 // ExtractSecurityGroups returns a slice of SecurityGroups contained in a single page of results.
-func ExtractSecurityGroups(page pagination.Page) ([]SecurityGroup, error) {
-	r := page.(SecurityGroupPage)
+func ExtractSecurityGroups(r pagination.Page) ([]SecurityGroup, error) {
 	var s struct {
 		SecurityGroups []SecurityGroup `json:"security_groups"`
 	}
-	err := r.ExtractInto(&s)
+	err := (r.(SecurityGroupPage)).ExtractInto(&s)
 	return s.SecurityGroups, err
 }