diff --git a/src/compiler/symbolWalker.ts b/src/compiler/symbolWalker.ts
index fda1febfb04..ade9e12d039 100644
--- a/src/compiler/symbolWalker.ts
+++ b/src/compiler/symbolWalker.ts
@@ -13,19 +13,17 @@ namespace ts {
         return getSymbolWalker;
 
         function getSymbolWalker(accept: (symbol: Symbol) => boolean = () => true): SymbolWalker {
-            let visitedTypes = createMap<Type>(); // Key is id as string
-            let visitedSymbols = createMap<Symbol>(); // Key is id as string
+            const visitedTypes = createMap<Type>(); // Key is id as string
+            const visitedSymbols = createMap<Symbol>(); // Key is id as string
 
             return {
-                walkType: type =>
-                {
+                walkType: type => {
                     visitedTypes.clear();
                     visitedSymbols.clear();
                     visitType(type);
                     return { visitedTypes: arrayFrom(visitedTypes.values()), visitedSymbols: arrayFrom(visitedSymbols.values()) };
                 },
-                walkSymbol: symbol =>
-                {
+                walkSymbol: symbol => {
                     visitedTypes.clear();
                     visitedSymbols.clear();
                     visitSymbol(symbol);
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 2182f02afe0..37e12cc9d29 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -2674,9 +2674,9 @@ namespace ts {
     /* @internal */
     export interface SymbolWalker {
         /** Note: Return values are not ordered. */
-        walkType(root: Type) : { visitedTypes: ReadonlyArray<Type>, visitedSymbols: ReadonlyArray<Symbol> };
+        walkType(root: Type): { visitedTypes: ReadonlyArray<Type>, visitedSymbols: ReadonlyArray<Symbol> };
         /** Note: Return values are not ordered. */
-        walkSymbol(root: Symbol) : { visitedTypes: ReadonlyArray<Type>, visitedSymbols: ReadonlyArray<Symbol> };
+        walkSymbol(root: Symbol): { visitedTypes: ReadonlyArray<Type>, visitedSymbols: ReadonlyArray<Symbol> };
     }
 
     export interface SymbolDisplayBuilder {
diff --git a/src/harness/unittests/symbolWalker.ts b/src/harness/unittests/symbolWalker.ts
index 8857fb66e0e..6d38fbb5198 100644
--- a/src/harness/unittests/symbolWalker.ts
+++ b/src/harness/unittests/symbolWalker.ts
@@ -28,7 +28,7 @@ export default function foo(a: number, b: Bar): void {}`, (file, checker) => {
             let foundCount = 0;
             let stdLibRefSymbols = 0;
             const expectedSymbols = ["default", "a", "b", "Bar", "x", "y", "history"];
-            let walker = checker.getSymbolWalker(symbol => {
+            const walker = checker.getSymbolWalker(symbol => {
                 const isStdLibSymbol = forEach(symbol.declarations, d => {
                     return getSourceFileOfNode(d).hasNoDefaultLib;
                 });