diff --git a/lib/fcm.rb b/lib/fcm.rb
index 16403c1..c29008a 100644
--- a/lib/fcm.rb
+++ b/lib/fcm.rb
@@ -295,16 +295,17 @@ def jwt_token
 
   def credentials_error_msg(param)
     error_msg = 'credentials must be an IO-like ' \
-      'object or path You passed'
+      'object or path '
     param_type = ''
 
     if param.nil? 
-      param_type = " nil"
+      param_type = ' You passed nil'
     else
-      param_type = "a #{param.class.name}"
+      param_type = " You passed a #{param.class.name}"
     end
-    
-    raise InvalidCredentialError, "#{error_msg} #{param_type}"
+
+    error_msg += param_type
+    raise InvalidCredentialError, error_msg
   end
 
   def filename_or_io_like?(path)