diff --git a/setup.py b/setup.py
index 101fecd5e..0397c5526 100644
--- a/setup.py
+++ b/setup.py
@@ -506,9 +506,9 @@ class pil_build_ext(build_ext):
 
         for f in feature:
             if not getattr(feature, f) and feature.require(f):
-                if feature in ('jpeg', 'libz'):
+                if f in ('jpeg', 'libz'):
                     raise ValueError('%s is required unless explicitly disabled'
-                                     + ' using --disable-%s, aborting' %
+                                     ' using --disable-%s, aborting' %
                                      (f, f))
                 raise ValueError(
                     '--enable-%s requested but %s not found, aborting.'