diff --git a/worker/peergrouper/controllertracker.go b/worker/peergrouper/controllertracker.go
index b8961b315f0..cde9331fdf6 100644
--- a/worker/peergrouper/controllertracker.go
+++ b/worker/peergrouper/controllertracker.go
@@ -239,6 +239,9 @@ func (c *controllerTracker) hasNodeChanged() (bool, error) {
 }
 
 func (c *controllerTracker) hostPendingProvisioning() (bool, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
 	status, err := c.host.Status()
 	if err != nil {
 		return false, errors.Trace(err)