diff --git a/src/theme/book.js b/src/theme/book.js
index 4d395821..83295de9 100644
--- a/src/theme/book.js
+++ b/src/theme/book.js
@@ -120,7 +120,7 @@ function playground_text(playground) {
             code: text,
             edition: edition
         };
-        alert(params.edition);
+
         if (text.indexOf("#![feature") !== -1) {
             params.version = "nightly";
         }