diff --git a/acme/errors.go b/acme/errors.go
index 95c006b7..3158b19b 100644
--- a/acme/errors.go
+++ b/acme/errors.go
@@ -337,7 +337,10 @@ func (e *Error) StatusCode() int {
 
 // Error allows AError to implement the error interface.
 func (e *Error) Error() string {
-	return e.Detail
+	if e.Err == nil {
+		return e.Detail
+	}
+	return e.Err.Error()
 }
 
 // Cause returns the internal error and implements the Causer interface.