diff --git a/youtube_dl/downloader/external.py b/youtube_dl/downloader/external.py
index 3a73cee1c..3ff1f9ed4 100644
--- a/youtube_dl/downloader/external.py
+++ b/youtube_dl/downloader/external.py
@@ -210,6 +210,7 @@ class FFmpegFD(ExternalFD):
             # args += ['-http_proxy', proxy]
             env = os.environ.copy()
             compat_setenv('HTTP_PROXY', proxy, env=env)
+            compat_setenv('http_proxy', proxy, env=env)
 
         protocol = info_dict.get('protocol')