diff --git a/compose/config/validation.py b/compose/config/validation.py
index 46b891b71..19faa0bce 100644
--- a/compose/config/validation.py
+++ b/compose/config/validation.py
@@ -143,7 +143,7 @@ def process_errors(errors, service_name=None):
             if len(validator) >= 2:
                 first_type = anglicize_validator(validator[0])
                 last_type = anglicize_validator(validator[-1])
-                types_from_validator = "{}{}".format(first_type, ", ".join(validator[1:-1]))
+                types_from_validator = "{}".format(", ".join([first_type] + validator[1:-1]))
 
                 msg = "{} or {}".format(
                     types_from_validator,
@@ -163,7 +163,6 @@ def process_errors(errors, service_name=None):
         Inspecting the context value of a ValidationError gives us information about
         which sub schema failed and which kind of error it is.
         """
-
         required = [context for context in error.context if context.validator == 'required']
         if required:
             return required[0].message