diff --git a/Lib/distutils/command/install.py b/Lib/distutils/command/install.py
index 01ea005..cf45004 100644
--- a/Lib/distutils/command/install.py
+++ b/Lib/distutils/command/install.py
@@ -226,7 +226,7 @@
             # Otherwise, just tack the "fallback postfix" onto the
             # user-specified prefix.
 
-            return apply (os.join, (my_prefix,) + fallback_postfix)
+            return apply (os.path.join, (my_prefix,) + fallback_postfix)
 
     # replace_sys_prefix ()