diff --git a/update.py b/update.py
index 7aa5e736..dab3b8c2 100755
--- a/update.py
+++ b/update.py
@@ -79,6 +79,9 @@ apks = []
 for apkfile in glob.glob(os.path.join('repo','*.apk')):
 
     apkfilename = apkfile[5:]
+    if apkfilename.find(' ') != -1:
+        print "No spaces in APK filenames!"
+        sys.exit(1)
     srcfilename = apkfilename[:-4] + "_src.tar.gz"
 
     if not options.quiet: