diff --git a/var/spack/packages/python/package.py b/var/spack/packages/python/package.py
index 2213244d6d7..920629e9109 100644
--- a/var/spack/packages/python/package.py
+++ b/var/spack/packages/python/package.py
@@ -117,11 +117,10 @@ def python_ignore(self, ext_pkg, args):
 
         # Ignore pieces of setuptools installed by other packages.
         if ext_pkg.name != 'py-setuptools':
-            patterns.append(r'/site\.pyc?$')
+            patterns.append(r'/site.*\.pyc?$')
             patterns.append(r'setuptools\.pth')
             patterns.append(r'bin/easy_install[^/]*$')
             patterns.append(r'setuptools.*egg$')
-        patterns.append(r'__pycache__/.*.pyc$')
 
         return match_predicate(ignore_arg, patterns)