--- numpy/distutils/command/install.py
+++ numpy/distutils/command/install.py
@@ -58,7 +58,7 @@
             need_rewrite = False
             for l in f.readlines():
                 l = l.rstrip()
-                if ' ' in l:
+                if ' ' in l and '%dir ' not in l:
                     need_rewrite = True
                     l = '"%s"' % (l)
                 lines.append(l)