diff --git a/nibabel/deprecator.py b/nibabel/deprecator.py
index 7f8a420756..32a7c6835c 100644
--- a/nibabel/deprecator.py
+++ b/nibabel/deprecator.py
@@ -146,7 +146,7 @@ def __call__(self, message, since='', until='',
         if since:
             messages.append('* deprecated from version: ' + since)
         if until:
-            messages.append('* {} {} as of version: {}'.format(
+            messages.append('* {0} {1} as of version: {2}'.format(
                 "Raises" if self.is_bad_version(until) else "Will raise",
                 error_class,
                 until))