diff --git a/lib/pure/httpclient.nim b/lib/pure/httpclient.nim
index 67ba8cf2ba..7686d15bde 100644
--- a/lib/pure/httpclient.nim
+++ b/lib/pure/httpclient.nim
@@ -523,7 +523,7 @@ proc generateHeaders(requestUrl: Uri, httpMethod: HttpMethod, headers: HttpHeade
   # Proxy auth header.
   if not proxy.isNil and proxy.auth != "":
     let auth = base64.encode(proxy.auth)
-    add(result, "Proxy-Authorization: basic " & auth & httpNewLine)
+    add(result, "Proxy-Authorization: Basic " & auth & httpNewLine)
 
   for key, val in headers:
     add(result, key & ": " & val & httpNewLine)