diff --git a/lib/core/option.py b/lib/core/option.py
index 5767747c1..b8db7dc4e 100644
--- a/lib/core/option.py
+++ b/lib/core/option.py
@@ -1196,8 +1196,8 @@ def _setHTTPExtraHeaders():
         conf.headers = conf.headers.split("\n") if "\n" in conf.headers else conf.headers.split("\\n")
 
         for headerValue in conf.headers:
-            if headerValue.count(':') == 1:
-                header, value = (_.lstrip() for _ in headerValue.split(":"))
+            if headerValue.count(':') > 1:
+                header, value = (_.lstrip() for _ in headerValue.split(":", 1))
 
                 if header and value:
                     conf.httpHeaders.append((header, value))