diff --git a/packages/babel-plugin-transform-block-scoping/src/index.js b/packages/babel-plugin-transform-block-scoping/src/index.js
index 7a671d2445a5..a652b77c5085 100644
--- a/packages/babel-plugin-transform-block-scoping/src/index.js
+++ b/packages/babel-plugin-transform-block-scoping/src/index.js
@@ -543,7 +543,7 @@ class BlockScoping {
     this.hoistVarDeclarations();
 
     // turn outsideLetReferences into an array
-    const args = [...outsideRefs.values()].map(node => t.cloneNode(node));
+    const args = Array.from(outsideRefs.values(), node => t.cloneNode(node));
     const params = args.map(id => t.cloneNode(id));
 
     const isSwitch = this.blockPath.isSwitchStatement();