diff --git a/Lib/distutils/command/config.py b/Lib/distutils/command/config.py
index b6f5ad1dc5a..3bd537a6e80 100644
--- a/Lib/distutils/command/config.py
+++ b/Lib/distutils/command/config.py
@@ -151,7 +151,8 @@ def _link (self, body,
                                       library_dirs=library_dirs,
                                       target_lang=lang)
 
-        prog = prog + self.compiler.exe_extension
+        if self.compiler.exe_extension is not None:
+            prog = prog + self.compiler.exe_extension
         self.temp_files.append(prog)
 
         return (src, obj, prog)