diff --git a/ansible/group_vars/all/kolla b/ansible/group_vars/all/kolla
index bd2652c2cd9b444f67addd27beb362653c2db2a1..3c98b95f5f9565ee2cab98c23ce253e9b32bc52b 100644
--- a/ansible/group_vars/all/kolla
+++ b/ansible/group_vars/all/kolla
@@ -289,9 +289,9 @@ kolla_build_blocks: {}
 # Dict mapping image customization variable names to their values.
 # Each variable takes the form:
 # <image name>_<customization>_<operation>
-# Hyphens in the image name are replaced with underscores. The customization is
-# most commonly packages. The operation should be one of override, append or
-# remove. The value should be a list.
+# Hyphens in the image name must be replaced with underscores. The
+# customization is most commonly packages. The operation should be one of
+# override, append or remove. The value should be a list.
 kolla_build_customizations: {}
 
 ###############################################################################
diff --git a/ansible/roles/kolla-build/defaults/main.yml b/ansible/roles/kolla-build/defaults/main.yml
index 66de5825f559729d72aebd2f23f32e531baca9d0..68ca8c38f2d77a1dc91a264981b8cd2a179d6d11 100644
--- a/ansible/roles/kolla-build/defaults/main.yml
+++ b/ansible/roles/kolla-build/defaults/main.yml
@@ -33,9 +33,9 @@ kolla_build_blocks: {}
 # Dict mapping image customization variable names to their values.
 # Each variable takes the form:
 # <image name>_<customization>_<operation>
-# Hyphens in the image name are replaced with underscores. The customization is
-# most commonly packages. The operation should be one of override, append or
-# remove. The value should be a list.
+# Hyphens in the image name must be replaced with underscores. The
+# customization is most commonly packages. The operation should be one of
+# override, append or remove. The value should be a list.
 kolla_build_customizations: {}
 
 # Free-form extra configuration for kolla-build.
diff --git a/etc/kayobe/kolla.yml b/etc/kayobe/kolla.yml
index 7e6da27def74760e181171a24b41f8bffd9a921a..74f805fad4a137648ec75f69567514e93bafa48f 100644
--- a/etc/kayobe/kolla.yml
+++ b/etc/kayobe/kolla.yml
@@ -109,9 +109,9 @@
 # Dict mapping image customization variable names to their values.
 # Each variable takes the form:
 # <image name>_<customization>_<operation>
-# Hyphens in the image name are replaced with underscores. The customization is
-# most commonly packages. The operation should be one of override, append or
-# remove. The value should be a list.
+# Hyphens in the image name must be replaced with underscores. The
+# customization is most commonly packages. The operation should be one of
+# override, append or remove. The value should be a list.
 #kolla_build_customizations:
 
 ###############################################################################