--- a/client/clienterror/matcher.go
+++ b/client/clienterror/matcher.go
@@ -2,6 +2,7 @@ package clienterror
 
 import (
 	"crypto/x509"
+	"errors"
 	"net/http"
 
 	"github.com/giantswarm/microerror"
@@ -101,9 +102,7 @@ func IsServiceUnavailableError(err error) bool {
 // a x509.UnknownAuthorityError
 func IsCertificateSignedByUnknownAuthorityError(err error) bool {
 	if clientErr, ok := err.(*APIError); ok {
-		if _, certErrorOK := clientErr.OriginalError.(x509.UnknownAuthorityError); certErrorOK {
-			return true
-		}
+		return errors.As(clientErr.OriginalError, &x509.UnknownAuthorityError{})
 	}
 
 	return false