diff --git a/autopep8.py b/autopep8.py
index 5df1a1bd..76004856 100755
--- a/autopep8.py
+++ b/autopep8.py
@@ -1278,7 +1278,9 @@ def fix_e721(self, result):
                 _prefix = "".join(_tmp[:-1])
 
             if match.groups()[0] is None:
-                fix_line = f"{_prefix} isinstance({_type_comp}{target[end:-1]}){target[-1:]}"
+                _suffix = target[-1:]
+                _target = f"{_type_comp}{target[end:-1]}"
+                fix_line = f"{_prefix} isinstance({_target}){_suffix}"
             else:
                 fix_line = f"{_prefix} isinstance({_type_comp}){target[end:]}"
             self.source[line_index] = fix_line