diff --git a/test/mocha/mangle-debug.js b/test/mocha/mangle-debug.js
index a6377514..6b1c8405 100644
--- a/test/mocha/mangle-debug.js
+++ b/test/mocha/mangle-debug.js
@@ -4,39 +4,39 @@ var assert = require("assert");
 describe("mangle_properties 'debug' option ", function() {
     it("Should test the 'debug' option of mangle_properties works with no cache passed", function() {
         var js = 'var o = {}; o.foo = "bar";';
-		
-		var ast = Uglify.parse(js);
-		ast.figure_out_scope();
-		ast = Uglify.mangle_properties(ast, {
-			debug: true
-		});
-		
-		var stream = Uglify.OutputStream();
-		ast.print(stream);
-		var result = stream.toString();
-		
-		// Should match: var o={};o._$foo$NNN$="bar";
-		// where NNN is a number.
+        
+        var ast = Uglify.parse(js);
+        ast.figure_out_scope();
+        ast = Uglify.mangle_properties(ast, {
+            debug: true
+        });
+        
+        let stream = Uglify.OutputStream();
+        ast.print(stream);
+        var result = stream.toString();
+        
+        // Should match: var o={};o._$foo$NNN$="bar";
+        // where NNN is a number.
         assert(/var o=\{\};o\._\$foo\$\d+\$_="bar";/.test(result));
     });
-	
+    
     it("Should test the 'debug' option of mangle_properties works with a cache passed", function() {
         var js = 'var o = {}; o.foo = "bar";';
-		
-		var ast = Uglify.parse(js);
-		ast.figure_out_scope();
-		ast = Uglify.mangle_properties(ast, {
-			cache: {
-				cname: -1,
-				props: new Uglify.Dictionary()
-			},
-			debug: true
-		});
-		
-		var stream = Uglify.OutputStream();
-		ast.print(stream);
-		var result = stream.toString();
-		
-		assert.strictEqual(result, 'var o={};o._$foo$_="bar";');
+        
+        var ast = Uglify.parse(js);
+        ast.figure_out_scope();
+        ast = Uglify.mangle_properties(ast, {
+            cache: {
+                cname: -1,
+                props: new Uglify.Dictionary()
+            },
+            debug: true
+        });
+        
+        let stream = Uglify.OutputStream();
+        ast.print(stream);
+        var result = stream.toString();
+        
+        assert.strictEqual(result, 'var o={};o._$foo$_="bar";');
     });
 });