diff --git a/res/res_monitor.c b/res/res_monitor.c
index b86ea109e3..76c43e1a8c 100644
--- a/res/res_monitor.c
+++ b/res/res_monitor.c
@@ -388,6 +388,8 @@ int AST_OPTIONAL_API_NAME(ast_monitor_start)(struct ast_channel *chan, const cha
 		} else
 			monitor->write_stream = NULL;
 
+		ast_channel_insmpl_set(chan, 0);
+		ast_channel_outsmpl_set(chan, 0);
 		ast_channel_monitor_set(chan, monitor);
 		ast_monitor_set_state(chan, AST_MONITOR_RUNNING);
 		/* so we know this call has been monitored in case we need to bill for it or something */