--- a/netwerk/sctp/datachannel/DataChannel.cpp
+++ b/netwerk/sctp/datachannel/DataChannel.cpp
@@ -608,17 +608,17 @@ DataChannelConnection::CompleteConnect(T
       opt_len = (socklen_t)sizeof(struct sctp_paddrparams);
       r = usrsctp_getsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_PEER_ADDR_PARAMS,
                              &paddrparams, &opt_len);
       if (r < 0) {
         LOG(("usrsctp_getsockopt failed: %d", r));
       } else {
         // draft-ietf-rtcweb-data-channel-13 section 5: max initial MTU IPV4 1200, IPV6 1280
         paddrparams.spp_pathmtu = 1200; // safe for either
-        paddrparams.spp_flags &= !SPP_PMTUD_ENABLE;
+        paddrparams.spp_flags &= ~SPP_PMTUD_ENABLE;
         paddrparams.spp_flags |= SPP_PMTUD_DISABLE;
         opt_len = (socklen_t)sizeof(struct sctp_paddrparams);
         r = usrsctp_setsockopt(mMasterSocket, IPPROTO_SCTP, SCTP_PEER_ADDR_PARAMS,
                                &paddrparams, opt_len);
         if (r < 0) {
           LOG(("usrsctp_getsockopt failed: %d", r));
         } else {
           LOG(("usrsctp: PMTUD disabled, MTU set to %u", paddrparams.spp_pathmtu));