diff --git a/lib/http/server.js b/lib/http/server.js
index b38d7534..23fb3d97 100644
--- a/lib/http/server.js
+++ b/lib/http/server.js
@@ -279,6 +279,7 @@ HTTPServer.prototype.initRouter = function initRouter() {
     }
 
     const height = await this.chain.getHeight(hash);
+    const confirmations = this.chain.height - height;
 
     res.send(200, block.getJSON(this.network, view, height, confirmations));
   });