diff --git a/ansible/group_vars/all/kolla b/ansible/group_vars/all/kolla
index 7df5f0426a0626531d84d792518426b6c2c0dfca..732d745ee08dc707530740378c8e9a4fc63e06cb 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 f8f0a482cc946cc0f638c3b62dce7e757d815337..b9fa5d7fc9f521bbee37790827c1e170feed4141 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:
 
 ###############################################################################