diff --git a/Doc/tools/sphinx-build.py b/Doc/tools/sphinx-build.py
index ed2366b..94a8df8 100644
--- a/Doc/tools/sphinx-build.py
+++ b/Doc/tools/sphinx-build.py
@@ -11,14 +11,14 @@
 
 if __name__ == '__main__':
 
-#    if sys.version_info[:3] < (2, 5, 1):
-#        print >>sys.stderr, """\
-#Error: Sphinx needs to be executed with Python 2.5.1 or newer
-#(If you run this from the Makefile, you can set the PYTHON variable
-#to the path of an alternative interpreter executable, e.g.,
-#``make html PYTHON=python2.5``).
-#"""
-#        sys.exit(1)
+    if sys.version_info[:3] < (2, 4, 0):
+        print >>sys.stderr, """\
+Error: Sphinx needs to be executed with Python 2.4 or newer
+(If you run this from the Makefile, you can set the PYTHON variable
+to the path of an alternative interpreter executable, e.g.,
+``make html PYTHON=python2.5``).
+"""
+        sys.exit(1)
 
     from sphinx import main
     sys.exit(main(sys.argv))