diff --git a/lib/faraday/error.rb b/lib/faraday/error.rb
index 64e6afbed..af40c18ea 100644
--- a/lib/faraday/error.rb
+++ b/lib/faraday/error.rb
@@ -85,7 +85,7 @@ def initialize(exc = 'timeout', response = nil)
 
   # Raised by Faraday::Response::RaiseError in case of a nil status in response.
   class NilStatusError < ServerError
-    def initialize(_exc, response: nil)
+    def initialize(_exc, response = nil)
       message = 'http status could not be derived from the server response'
       super(message, response)
     end