diff --git a/Lib/decimal.py b/Lib/decimal.py
index 04bf5c2..19cc50f 100644
--- a/Lib/decimal.py
+++ b/Lib/decimal.py
@@ -3665,6 +3665,8 @@
         if self._is_special:
             sign = _format_sign(self._sign, spec)
             body = str(self.copy_abs())
+            if spec['type'] == '%':
+                body += '%'
             return _format_align(sign, body, spec)
 
         # a type of None defaults to 'g' or 'G', depending on context