diff --git a/src/engine/blocks.js b/src/engine/blocks.js
index 189a595be03..28995a7f407 100644
--- a/src/engine/blocks.js
+++ b/src/engine/blocks.js
@@ -845,7 +845,7 @@ class Blocks {
     getAllVariableAndListReferences (optBlocks, optIncludeBroadcast) {
         const blocks = optBlocks ? optBlocks : this._blocks;
         const allReferences = Object.create(null);
-        for (const blockId in blocks) {
+        for (const blockId of Object.keys(blocks)) {
             let varOrListField = null;
             let varType = null;
             if (blocks[blockId].fields.VARIABLE) {
diff --git a/src/engine/target.js b/src/engine/target.js
index c8bd5094fa5..6ed5747b561 100644
--- a/src/engine/target.js
+++ b/src/engine/target.js
@@ -747,8 +747,7 @@ class Target extends EventEmitter {
         }
         // Rename any local variables that were missed above because they aren't
         // referenced by any blocks
-        for (const id in unreferencedLocalVarIds) {
-            const varId = unreferencedLocalVarIds[id];
+        for (const varId of unreferencedLocalVarIds) {
             const name = this.variables[varId].name;
             const type = this.variables[varId].type;
             renameConflictingLocalVar(varId, name, type);