diff --git a/Lib/urlparse.py b/Lib/urlparse.py
index a019a7b..e5528fa 100644
--- a/Lib/urlparse.py
+++ b/Lib/urlparse.py
@@ -187,11 +187,15 @@
             v = SplitResult(scheme, netloc, url, query, fragment)
             _parse_cache[key] = v
             return v
-        if url.endswith(':') or not url[i+1].isdigit():
-            for c in url[:i]:
-                if c not in scheme_chars:
-                    break
-            else:
+        for c in url[:i]:
+            if c not in scheme_chars:
+                break
+        else:
+            try:
+                # make sure "url" is not actually a port number (in which case
+                # "scheme" is really part of the path
+                _testportnum = int(url[i+1:])
+            except ValueError:
                 scheme, url = url[:i].lower(), url[i+1:]
 
     if url[:2] == '//':