diff --git a/package.json b/package.json
index ecfc42a1..2e794d08 100644
--- a/package.json
+++ b/package.json
@@ -74,7 +74,7 @@
     "acorn-dynamic-import": "^4.0.0",
     "acorn-jsx": "^5.0.1",
     "chalk": "^2.4.2",
-    "magic-string": "^0.25.3",
+    "magic-string": "0.25.3",
     "minimist": "^1.2.0",
     "regexpu-core": "^4.5.4"
   }
diff --git a/src/program/BlockStatement.js b/src/program/BlockStatement.js
index b93cf267..fce1af69 100644
--- a/src/program/BlockStatement.js
+++ b/src/program/BlockStatement.js
@@ -16,6 +16,7 @@ export default class BlockStatement extends Node {
 		this.scope = new Scope({
 			block: !this.isFunctionBlock,
 			parent: this.parent.findScope(false),
+			parentType: this.parent.type,
 			declare: id => this.createdDeclarations.push(id)
 		});
 
diff --git a/src/program/Scope.js b/src/program/Scope.js
index bb93d3e2..6fa430a3 100644
--- a/src/program/Scope.js
+++ b/src/program/Scope.js
@@ -5,6 +5,7 @@ export default function Scope(options) {
 	options = options || {};
 
 	this.parent = options.parent;
+	this.parentType = options.parentType;
 	this.isBlockScope = !!options.block;
 	this.createDeclarationCallback = options.declare;
 
@@ -108,6 +109,23 @@ Scope.prototype = {
 		);
 	},
 
+	findDeclarationScope(name, initialScope = this) {
+		if (
+			this.declarations[name] ||
+			(this.blockScopedDeclarations && this.blockScopedDeclarations[name]) ||
+			// Creation of new lexical environment for `catch` block: https://github.com/bublejs/buble/pull/240
+			this.parentType === 'CatchClause'
+		) {
+			return this;
+		}
+
+		if (this.parent) {
+			return this.parent.findDeclarationScope(name, initialScope);
+		}
+
+		return initialScope;
+	},
+
 	// Sometimes, block scope declarations change name during transpilation
 	resolveName(name) {
 		const declaration = this.findDeclaration(name);
diff --git a/src/program/types/ForInStatement.js b/src/program/types/ForInStatement.js
index c368c019..36674788 100644
--- a/src/program/types/ForInStatement.js
+++ b/src/program/types/ForInStatement.js
@@ -10,6 +10,7 @@ export default class ForInStatement extends LoopStatement {
 		this.scope = new Scope({
 			block: true,
 			parent: this.parent.findScope(false),
+			parentType: this.parent.type,
 			declare: id => this.createdDeclarations.push(id)
 		});
 
diff --git a/src/program/types/ForOfStatement.js b/src/program/types/ForOfStatement.js
index 7dcad961..9ec25e4d 100644
--- a/src/program/types/ForOfStatement.js
+++ b/src/program/types/ForOfStatement.js
@@ -15,6 +15,7 @@ export default class ForOfStatement extends LoopStatement {
 		this.scope = new Scope({
 			block: true,
 			parent: this.parent.findScope(false),
+			parentType: this.parent.type,
 			declare: id => this.createdDeclarations.push(id)
 		});
 
diff --git a/src/program/types/ForStatement.js b/src/program/types/ForStatement.js
index 617a3884..fffeb8ce 100644
--- a/src/program/types/ForStatement.js
+++ b/src/program/types/ForStatement.js
@@ -9,6 +9,7 @@ export default class ForStatement extends LoopStatement {
 		this.scope = new Scope({
 			block: true,
 			parent: this.parent.findScope(false),
+			parentType: this.parent.type,
 			declare: id => this.createdDeclarations.push(id)
 		});
 
diff --git a/src/program/types/Identifier.js b/src/program/types/Identifier.js
index 5aa78784..1f46b2c0 100644
--- a/src/program/types/Identifier.js
+++ b/src/program/types/Identifier.js
@@ -12,7 +12,7 @@ export default class Identifier extends Node {
 			return this.parent.body.scope;
 		}
 
-		return this.parent.findScope(functionScope);
+		return this.parent.findScope(functionScope).findDeclarationScope(this.name);
 	}
 
 	initialise(transforms) {
diff --git a/test/samples/block-scoping.js b/test/samples/block-scoping.js
index a1b0bf99..eff45a36 100644
--- a/test/samples/block-scoping.js
+++ b/test/samples/block-scoping.js
@@ -642,5 +642,62 @@ module.exports = [
 			var x = 1;
 			for (var x$1 in { x: x$1 }) {}
 		`
+	},
+
+	{
+		description: 'deconflicts blocks in switch-statement and parent function scope',
+		options: { transforms: { letConst: true } },
+		input: `
+			function foo() {
+				const n = 1;
+				for (let i = 0; i < n; i++) {
+					const o = n;
+					switch (n) {
+						case 1:
+							const n = 12;
+							console.log(n);
+							break;
+					}
+				}
+			}
+		`,
+		output:`
+			function foo() {
+				var n = 1;
+				for (var i = 0; i < n; i++) {
+					var o = n;
+					switch (n) {
+						case 1:
+							var n$1 = 12;
+							console.log(n$1);
+							break;
+					}
+				}
+			}
+		`
+	},
+	{
+		description: 'deconflicts blocks in class declaration and for statement',
+		options: { transforms: { letConst: true, classes: false } },
+		input: `
+			class e {
+				run() {
+					if(this instanceof e) {
+						for(let e = 0; e < 1; e++) console.log('here');
+					}
+				}
+			}
+			new e().run();
+		`,
+		output:`
+			class e {
+				run() {
+					if(this instanceof e) {
+						for(var e$1 = 0; e$1 < 1; e$1++) { console.log('here'); }
+					}
+				}
+			}
+			new e().run();
+		`
 	}
 ];