diff --git a/lib/ansible/module_utils/ec2.py b/lib/ansible/module_utils/ec2.py
index 2e45ef1b0e..a8c60c7ee9 100644
--- a/lib/ansible/module_utils/ec2.py
+++ b/lib/ansible/module_utils/ec2.py
@@ -105,7 +105,7 @@ def boto3_conn(module, conn_type=None, resource=None, region=None, endpoint=None
     try:
         return _boto3_conn(conn_type=conn_type, resource=resource, region=region, endpoint=endpoint, **params)
     except ValueError as e:
-        module.fail_json(msg="Couldn't connect to AWS: " % to_native(e))
+        module.fail_json(msg="Couldn't connect to AWS: %s" % to_native(e))
     except (botocore.exceptions.ProfileNotFound, botocore.exceptions.PartialCredentialsError) as e:
         module.fail_json(msg=to_native(e))
     except botocore.exceptions.NoRegionError as e: