diff --git a/modules/activitypub/client.go b/modules/activitypub/client.go
index c23f3b18f..2e872d2db 100644
--- a/modules/activitypub/client.go
+++ b/modules/activitypub/client.go
@@ -106,7 +106,7 @@ func (c *Client) NewRequest(b []byte, to string) (req *http.Request, err error)
 	}
 	req.Header.Add("Content-Type", ActivityStreamsContentType)
 	req.Header.Add("Accept-Charset", "utf-8")
-	req.Header.Add("Date", fmt.Sprintf("%s GMT", time.Now().UTC().Format(time.RFC1123)))
+	req.Header.Add("Date", fmt.Sprintf("%s UTC", time.Now().UTC().Format(time.RFC1123)))
 
 	signer, _, err := httpsig.NewSigner(c.algs, c.digestAlg, c.postHeaders, httpsig.Signature, httpsigExpirationTime)
 	if err != nil {