Unit test for the Extract function.
diff --git a/openstack/compute/v2/extensions/diskconfig/results.go b/openstack/compute/v2/extensions/diskconfig/results.go
index 05a29a8..10ec2da 100644
--- a/openstack/compute/v2/extensions/diskconfig/results.go
+++ b/openstack/compute/v2/extensions/diskconfig/results.go
@@ -44,7 +44,7 @@
 	casted := page.(servers.ServerPage).Body
 
 	type server struct {
-		DiskConfig string `mapstructure:"OS-CDF:diskConfig"`
+		DiskConfig string `mapstructure:"OS-DCF:diskConfig"`
 	}
 	var response struct {
 		Servers []server `mapstructure:"servers"`