diff --git a/packages/babel-plugin-transform-es2015-block-scoping/src/index.js b/packages/babel-plugin-transform-es2015-block-scoping/src/index.js
index f9e27de7b6..5422eaf828 100644
--- a/packages/babel-plugin-transform-es2015-block-scoping/src/index.js
+++ b/packages/babel-plugin-transform-es2015-block-scoping/src/index.js
@@ -459,8 +459,8 @@ class BlockScoping {
     this.hoistVarDeclarations();
 
     // turn outsideLetReferences into an array
-    const params = values(outsideRefs);
     const args = values(outsideRefs);
+    const params = args.map(id => t.clone(id));
 
     const isSwitch = this.blockPath.isSwitchStatement();
 
diff --git a/packages/babel-preset-es2015/test/fixtures/preset-options/6025/actual.js b/packages/babel-preset-es2015/test/fixtures/preset-options/6025/actual.js
new file mode 100644
index 0000000000..188e09baa5
--- /dev/null
+++ b/packages/babel-preset-es2015/test/fixtures/preset-options/6025/actual.js
@@ -0,0 +1,8 @@
+for (let path of c) {
+  path;
+  () => path;
+}
+
+if (true) {
+  let path = false;
+}
diff --git a/packages/babel-preset-es2015/test/fixtures/preset-options/6025/expected.js b/packages/babel-preset-es2015/test/fixtures/preset-options/6025/expected.js
new file mode 100644
index 0000000000..798a5ae27b
--- /dev/null
+++ b/packages/babel-preset-es2015/test/fixtures/preset-options/6025/expected.js
@@ -0,0 +1,36 @@
+var _loop = function _loop(path) {
+  path;
+
+  (function () {
+    return path;
+  });
+};
+
+var _iteratorNormalCompletion = true;
+var _didIteratorError = false;
+var _iteratorError = undefined;
+
+try {
+  for (var _iterator = c[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
+    var _path = _step.value;
+
+    _loop(_path);
+  }
+} catch (err) {
+  _didIteratorError = true;
+  _iteratorError = err;
+} finally {
+  try {
+    if (!_iteratorNormalCompletion && _iterator.return) {
+      _iterator.return();
+    }
+  } finally {
+    if (_didIteratorError) {
+      throw _iteratorError;
+    }
+  }
+}
+
+if (true) {
+  var path = false;
+}
diff --git a/packages/babel-preset-es2015/test/fixtures/preset-options/6025/options.json b/packages/babel-preset-es2015/test/fixtures/preset-options/6025/options.json
new file mode 100644
index 0000000000..70fe60f1ee
--- /dev/null
+++ b/packages/babel-preset-es2015/test/fixtures/preset-options/6025/options.json
@@ -0,0 +1,27 @@
+{
+  "plugins": [
+    "check-es2015-constants",
+    "transform-es2015-arrow-functions",
+    "transform-es2015-block-scoped-functions",
+    "transform-es2015-block-scoping",
+    "transform-es2015-classes",
+    "transform-es2015-computed-properties",
+    "transform-es2015-destructuring",
+    "transform-es2015-duplicate-keys",
+    "transform-es2015-for-of",
+    "transform-es2015-function-name",
+    "transform-es2015-literals",
+    "transform-es2015-object-super",
+    "transform-es2015-parameters",
+    "transform-es2015-shorthand-properties",
+    "transform-es2015-spread",
+    "transform-es2015-sticky-regex",
+    "transform-es2015-template-literals",
+    "transform-es2015-typeof-symbol",
+    "transform-es2015-unicode-regex",
+    "transform-regenerator",
+    "transform-exponentiation-operator",
+    "transform-async-to-generator",
+    "syntax-trailing-function-commas"
+  ]
+}