diff --git a/fhem/FHEM/00_MQTT2_CLIENT.pm b/fhem/FHEM/00_MQTT2_CLIENT.pm
index 21cc28ae0..00532ce5b 100644
--- a/fhem/FHEM/00_MQTT2_CLIENT.pm
+++ b/fhem/FHEM/00_MQTT2_CLIENT.pm
@@ -43,6 +43,7 @@ MQTT2_CLIENT_Initialize($)
     disable:1,0
     disabledForIntervals
     disconnectAfter
+    httpHeader
     ignoreRegexp
     lwt
     lwtRetain
@@ -107,6 +108,10 @@ MQTT2_CLIENT_connect($)
   $hash->{connecting} = 1 if($disco && !$hash->{connecting});
   $hash->{nextOpenDelay} = 5;
   $hash->{BUF}="";
+  if($hash->{DeviceName} =~ m/^wss?:/) {
+    $hash->{binary} = 1;
+    $hash->{header}{"Sec-WebSocket-Protocol"} = "mqtt";
+  }
   return DevIo_OpenDev($hash, $disco, "MQTT2_CLIENT_doinit", sub(){})
                 if($hash->{connecting});
 }
@@ -314,6 +319,14 @@ MQTT2_CLIENT_Attr(@)
     }
   }
 
+  if($attrName eq "httpHeader") {
+    $hash->{header} = {};
+    for my $kv (split(" ",$param[0])) {
+      my ($k, $v) = split(":", $kv, 2);
+      $hash->{header}{$k} = $v;
+    }
+  }
+
   my %h = (clientId=>1,lwt=>1,lwtRetain=>1,subscriptions=>1,SSL=>1,username=>1);
   if($init_done && $h{$attrName}) {
     delete($hash->{authError});
@@ -874,6 +887,13 @@ MQTT2_CLIENT_feedTheList($$$)
       inactivity, and will be automatically reopened when sending a command.
       </li><br>
 
+    <a id="MQTT2_CLIENT-attr-httpHeader"></a>
+    <li>header<br>
+      a list of space separated tuples of key:value, used to set the HTTP
+      header when MQTT is used over websocket.
+      </li><br>
+
+
     <a id="MQTT2_CLIENT-attr-ignoreRegexp"></a>
     <li>ignoreRegexp<br>
       if $topic:$message matches ignoreRegexp, then it will be silently ignored.
diff --git a/fhem/FHEM/DevIo.pm b/fhem/FHEM/DevIo.pm
index d7bc388f1..99f6cfce0 100644
--- a/fhem/FHEM/DevIo.pm
+++ b/fhem/FHEM/DevIo.pm
@@ -280,8 +280,9 @@ DevIo_SimpleWrite($$$;$)
 
   } elsif($hash->{TCPDev}) {
     if($hash->{WEBSOCKET}) {
-      $msg = Encode::encode('UTF-8', $msg) if($unicodeEncoding && !$hash->{binary});
-      $msg = DevIo_MaskWS($hash->{binary} ? 0x2:0x1, $msg)
+      $msg = Encode::encode('UTF-8', $msg)
+        if($unicodeEncoding && !$hash->{binary});
+      $msg = DevIo_MaskWS($hash->{binary} ? 0x2:0x1, $msg);
     }
     syswrite($hash->{TCPDev}, $msg);