diff --git a/Build.py b/Build.py
index 47643ff..279baa8 100755
--- a/Build.py
+++ b/Build.py
@@ -42,6 +42,19 @@ if config['pythonVersion'] != sys.version:
 if config['hasRsrcUpdate']:
     import icon, versionInfo
 
+def setupUPXFlags():
+    f = os.environ.get("UPX", "")
+    is24 = hasattr(sys, "version_info") and sys.version_info[:2] >= (2,4)
+    if iswin and is24:
+        # Binaries built with Visual Studio 7.1 require --strip-loadconf
+        # or they won't compress.
+        f = "--strip-loadconf " + f
+    f = "--best " + f
+    os.environ["UPX"] = f
+
+if config['hasUPX']:
+    setupUPXFlags()
+
 def build(spec):
     global SPECPATH, BUILDPATH, WARNFILE, rthooks
     rthooks = eval(open(os.path.join(HOMEPATH, 'rthooks.dat'), 'r').read())
diff --git a/doc/CHANGES.txt b/doc/CHANGES.txt
index 6b37c72..e4a12f6 100644
--- a/doc/CHANGES.txt
+++ b/doc/CHANGES.txt
@@ -22,6 +22,9 @@ Current changes since PyInstaller 1.0
    single-file executables, even when using the newest Python version!
  + (Linux) Ignore linux-gate.so while calculating dependencies (fix provided
    by Vikram Aggarwal).
+ + (Windows) With Python 2.4, setup UPX properly so to be able to compress
+   binaries generated with Visual Studio .NET 2003 (such as most of the
+   extensions).
 
 
 PyInstaller 1.0 (with respect to McMillan's Python Installer 5b5):