diff --git a/config/schema/webform.block.schema.yml b/config/schema/webform.block.schema.yml
index 58150e0f5e4a457d19fb07ed14a17511dde8c586..4795bc2544b2fa395c9792e3649c4b8d70907c25 100644
--- a/config/schema/webform.block.schema.yml
+++ b/config/schema/webform.block.schema.yml
@@ -2,9 +2,20 @@ block.settings.webform_block:
   type: block_settings
   label: 'Webforms block'
   mapping:
+    id:
+      type: string
+      label: Identifier
+      constraints:
+        Regex:
+          pattern: '/^[a-z0-9_]+$/'
+          message: "The %value machine name is not valid."
     webform_id:
       type: string
       label: Webform
+      constraints:
+        Regex:
+          pattern: '/^[a-z0-9_]+$/'
+          message: "The %value machine name is not valid."
     default_data:
       type: text
       label: 'Default webform submission data'
diff --git a/config/schema/webform.entity.webform.schema.yml b/config/schema/webform.entity.webform.schema.yml
index c917ee3626087af49be099895d33f48ed4e064f1..fc3cb0d919f3e7863f5d14f2b1a9eea1898e40c7 100644
--- a/config/schema/webform.entity.webform.schema.yml
+++ b/config/schema/webform.entity.webform.schema.yml
@@ -26,6 +26,10 @@
     id:
       type: string
       label: 'Machine name'
+      constraints:
+        Regex:
+          pattern: '/^[a-z0-9_]+$/'
+          message: "The %value machine name is not valid."
     title:
       type: label
       label: Title