diff --git a/src/blot/block.ts b/src/blot/block.ts
index fae2cca..f6de902 100644
--- a/src/blot/block.ts
+++ b/src/blot/block.ts
@@ -14,7 +14,9 @@ class BlockBlot extends FormatBlot {
   }
 
   format(name: string, value: any) {
-    if (name === this.statics.blotName && !value) {
+    if (Registry.query(name, Registry.Scope.BLOCK) == null) {
+      return;
+    } else if (name === this.statics.blotName && !value) {
       this.replaceWith(BlockBlot.blotName);
     } else {
       super.format(name, value);
diff --git a/test/unit/block.js b/test/unit/block.js
index 3d84899..0eb323b 100644
--- a/test/unit/block.js
+++ b/test/unit/block.js
@@ -48,5 +48,15 @@ describe('Block', function() {
       expect(container.children.length).toBe(3);
       expect(container.children.head.next.statics.blotName).toBe('video');
     });
+
+    it('ignore inline', function() {
+      let container = Registry.create('scroll');
+      let block = Registry.create('header', 1);
+      container.appendChild(block);
+      block.format('bold', true);
+      expect(container.domNode.innerHTML).toBe('<h1></h1>');
+      expect(container.children.head.statics.blotName).toBe('header');
+      expect(container.children.head.formats()).toEqual({ header: 'h1' });
+    });
   });
 });