diff -ru asterisk-13.21.0/main/bridge_channel.c asterisk-13.21.0_changed/main/bridge_channel.c
--- asterisk-13.21.0/main/bridge_channel.c	2018-05-01 22:01:46.000000000 +0200
+++ asterisk-13.21.0_changed/main/bridge_channel.c	2018-05-28 14:19:21.618145023 +0200
@@ -2648,6 +2648,7 @@
 	int res = 0;
 	struct ast_bridge_features *channel_features;
 	struct ast_channel *swap;
+	bool indicate_src_change = false;
 
 	ast_debug(1, "Bridge %s: %p(%s) is joining\n",
 		bridge_channel->bridge->uniqueid,
@@ -2715,12 +2716,16 @@
 		 */
 		if (!(bridge_channel->bridge->technology->capabilities
 			& AST_BRIDGE_CAPABILITY_MULTIMIX)) {
-			ast_indicate(bridge_channel->chan, AST_CONTROL_SRCCHANGE);
+			indicate_src_change = true;
 		}
 
 		bridge_channel_impart_signal(bridge_channel->chan);
 		ast_bridge_unlock(bridge_channel->bridge);
 
+		if (indicate_src_change) {
+			ast_indicate(bridge_channel->chan, AST_CONTROL_SRCCHANGE);
+		}
+
 		/* Must release any swap ref after unlocking the bridge. */
 		ao2_t_cleanup(swap, "Bridge push with swap successful");
 		swap = NULL;