diff --git a/common/errors.go b/common/errors.go
index 7259b29dc..5c31b8968 100644
--- a/common/errors.go
+++ b/common/errors.go
@@ -188,7 +188,7 @@ Theoretically it could be used to switch on the format string.
 	var err2 error = NewError("another kind of error")
 	...
 	// Error handling
-	switch err1.Data().(cmn.FmtError).Format {
+	switch err1.Data().(cmn.FmtError).Format() {
 		case "invalid username %v": ...
 		case "another kind of error": ...
 	    default: ...