diff --git a/scrapy/downloadermiddlewares/httpproxy.py b/scrapy/downloadermiddlewares/httpproxy.py
index fe7bf0e04..e1a076b74 100644
--- a/scrapy/downloadermiddlewares/httpproxy.py
+++ b/scrapy/downloadermiddlewares/httpproxy.py
@@ -50,13 +50,14 @@ class HttpProxyMiddleware:
                 creds, proxy_url = self._get_proxy(request.meta["proxy"], "")
         elif self.proxies:
             parsed = urlparse_cached(request)
-            scheme = parsed.scheme
+            _scheme = parsed.scheme
             if (
                 # 'no_proxy' is only supported by http schemes
-                scheme not in ("http", "https")
+                _scheme not in ("http", "https")
                 or not proxy_bypass(parsed.hostname)
-            ) and scheme in self.proxies:
+            ) and _scheme in self.proxies:
                 creds, proxy_url = self.proxies[scheme]
+                scheme = _scheme
 
         self._set_proxy_and_creds(request, proxy_url, creds, scheme)