diff --git a/lib/pleroma/web/activity_pub/activity_pub.ex b/lib/pleroma/web/activity_pub/activity_pub.ex
index 52f5a0c70..bd4ac6197 100644
--- a/lib/pleroma/web/activity_pub/activity_pub.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub.ex
@@ -776,7 +776,7 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
 
     date =
       NaiveDateTime.utc_now()
-      |> Timex.format!("{WDshort}, {D} {Mshort} {YYYY} {h24}:{m}:{s} GMT")
+      |> Timex.format!("{WDshort}, {0D} {Mshort} {YYYY} {h24}:{m}:{s} GMT")
 
     signature =
       Pleroma.Web.HTTPSignatures.sign(actor, %{