Fix old urllib/urllib2/urlparse usage.
diff --git a/Mac/BuildScript/build-installer.py b/Mac/BuildScript/build-installer.py
index 8e359ba..6156072 100755
--- a/Mac/BuildScript/build-installer.py
+++ b/Mac/BuildScript/build-installer.py
@@ -9,7 +9,8 @@
 
 Usage: see USAGE variable in the script.
 """
-import platform, os, sys, getopt, textwrap, shutil, urllib2, stat, time, pwd
+import platform, os, sys, getopt, textwrap, shutil, stat, time, pwd
+import urllib.request
 import grp
 
 INCLUDE_TIMESTAMP = 1
@@ -442,7 +443,7 @@
         if KNOWNSIZES.get(url) == size:
             print("Using existing file for", url)
             return
-    fpIn = urllib2.urlopen(url)
+    fpIn = urllib.request.urlopen(url)
     fpOut = open(fname, 'wb')
     block = fpIn.read(10240)
     try: