diff --git a/tests/simulator-ng.pl b/tests/simulator-ng.pl
index 32a4a38c9..3176c21ea 100755
--- a/tests/simulator-ng.pl
+++ b/tests/simulator-ng.pl
@@ -17,7 +17,8 @@ use SRTP;
 
 my ($NUM, $RUNTIME, $STREAMS, $PAYLOAD, $INTERVAL, $RTCP_INTERVAL, $STATS_INTERVAL)
 	= (1000, 30, 1, 160, 20, 5, 5);
-my ($NODEL, $IP, $IPV6, $KEEPGOING, $REINVITES, $PROTOS, $DEST, $SUITES, $NOENC, $RTCPMUX, $BUNDLE, $LAZY);
+my ($NODEL, $IP, $IPV6, $KEEPGOING, $REINVITES, $PROTOS, $DEST, $SUITES, $NOENC, $RTCPMUX, $BUNDLE, $LAZY,
+	$CHANGE_SSRC);
 GetOptions(
 		'no-delete'	=> \$NODEL,
 		'num-calls=i'	=> \$NUM,
@@ -38,6 +39,7 @@ GetOptions(
 		'rtcp-mux'	=> \$RTCPMUX,
 		'bundle'	=> \$BUNDLE,
 		'lazy-params'	=> \$LAZY,
+		'change-ssrc'   => \$CHANGE_SSRC,
 ) or die;
 
 ($IP || $IPV6) or die("at least one of --local-ip or --local-ipv6 must be given");
@@ -154,6 +156,7 @@ sub rtp_encrypt {
 
 	my ($pkt, $roc) = SRTP::encrypt_rtp(@$dctx{qw(crypto_suite rtp_session_key rtp_session_salt
 		rtp_session_auth_key rtp_roc rtp_mki rtp_mki_len unenc_srtp unauth_srtp)}, $r);
+	$roc == ($$dctx{rtp_roc} // 0) or print("ROC is now $roc\n");
 	$$dctx{rtp_roc} = $roc;
 
 	$NOENC{rtp_packet} = $pkt;
@@ -769,6 +772,21 @@ while (time() < $end) {
 		offer($c, 0, 1);
 		answer($c, 1, 0);
 	}
+
+	if ($CHANGE_SSRC && rand() < .001) {
+		my $c = $calls[rand(@calls)];
+		my $s = $$c{sides}[rand(2)];
+		my $st = rand($$s{num_streams});
+		my $d = (qw(in out))[rand(2)];
+		my $stc = $$s{trans_contexts}[$st];
+		my $ct = $$stc{$d};
+		if (defined($$ct{rtp_roc}) && $$stc{ssrc}) {
+			my $nssrc = rand(2 ** 32);
+			print("change SSRC from $$stc{ssrc} to $nssrc\n");
+			$$stc{ssrc} = $nssrc;
+			$$ct{roc} = 0;
+		}
+	}
 }
 
 if (!$NODEL) {