diff --git a/src/runtime/netpoll_aix.go b/src/runtime/netpoll_aix.go
index c936fbb70f..61becc247e 100644
--- a/src/runtime/netpoll_aix.go
+++ b/src/runtime/netpoll_aix.go
@@ -130,7 +130,9 @@ func netpollarm(pd *pollDesc, mode int) {
 
 // netpollBreak interrupts a poll.
 func netpollBreak() {
+	lock(&mtxpoll)
 	netpollwakeup()
+	unlock(&mtxpoll)
 }
 
 // netpoll checks for ready network connections.