diff --git a/Lib/distutils/command/install.py b/Lib/distutils/command/install.py
index 938922a..7182857 100644
--- a/Lib/distutils/command/install.py
+++ b/Lib/distutils/command/install.py
@@ -226,7 +226,7 @@
         # about needing recursive variable expansion (shudder).
 
         py_version = (string.split(sys.version))[0]
-        prefix = get_config_vars('prefix', 'exec_prefix')
+        (prefix, exec_prefix) = get_config_vars('prefix', 'exec_prefix')
         self.config_vars = {'dist_name': self.distribution.get_name(),
                             'dist_version': self.distribution.get_version(),
                             'dist_fullname': self.distribution.get_fullname(),