diff --git a/addons/flannel/0.21.5/install.sh b/addons/flannel/0.21.5/install.sh
index 731eeb69dd..70d10162ab 100644
--- a/addons/flannel/0.21.5/install.sh
+++ b/addons/flannel/0.21.5/install.sh
@@ -300,6 +300,7 @@ function flannel_already_applied() {
 
     flannel_ready_spinner
     check_network
+    check_udp_port
 }
 
 function flannel_post_init() {
diff --git a/addons/flannel/template/base/install.sh b/addons/flannel/template/base/install.sh
index 731eeb69dd..70d10162ab 100644
--- a/addons/flannel/template/base/install.sh
+++ b/addons/flannel/template/base/install.sh
@@ -300,6 +300,7 @@ function flannel_already_applied() {
 
     flannel_ready_spinner
     check_network
+    check_udp_port
 }
 
 function flannel_post_init() {