diff --git a/src/engine/runtime.js b/src/engine/runtime.js
index 5b26d8b8..6fc79426 100644
--- a/src/engine/runtime.js
+++ b/src/engine/runtime.js
@@ -1349,7 +1349,7 @@ class Runtime extends EventEmitter {
         // the category block icon.
         const iconURI = blockInfo.blockIconURI || categoryInfo.blockIconURI;
 
-        // All extension blocks have are from_extension
+        // All extension blocks have from_extension
         blockJSON.extensions.push('from_extension');
 
         // Allow easily detecting which blocks use default colors