diff --git a/editors/code/src/color_theme.ts b/editors/code/src/color_theme.ts
index d816f617d27..71113d374eb 100644
--- a/editors/code/src/color_theme.ts
+++ b/editors/code/src/color_theme.ts
@@ -69,7 +69,7 @@ function loadThemeNamed(themeName: string): ColorTheme {
         );
     }
 
-    let themePaths = vscode.extensions.all
+    const themePaths = vscode.extensions.all
         .filter(isTheme)
         .flatMap(ext => {
             return ext.packageJSON.contributes.themes
diff --git a/editors/code/src/commands/index.ts b/editors/code/src/commands/index.ts
index dc075aa8289..4501809e2ef 100644
--- a/editors/code/src/commands/index.ts
+++ b/editors/code/src/commands/index.ts
@@ -21,7 +21,7 @@ function collectGarbage(ctx: Ctx): Cmd {
 
 function showReferences(ctx: Ctx): Cmd {
     return (uri: string, position: lc.Position, locations: lc.Location[]) => {
-        let client = ctx.client;
+        const client = ctx.client;
         if (client) {
             vscode.commands.executeCommand(
                 'editor.action.showReferences',
diff --git a/editors/code/src/ctx.ts b/editors/code/src/ctx.ts
index a2a4e42a9b6..b882a8e52f7 100644
--- a/editors/code/src/ctx.ts
+++ b/editors/code/src/ctx.ts
@@ -20,7 +20,7 @@ export class Ctx {
     }
 
     async restartServer() {
-        let old = this.client;
+        const old = this.client;
         if (old) {
             await old.stop();
         }
diff --git a/editors/code/src/highlighting.ts b/editors/code/src/highlighting.ts
index fc7cd5a1cb8..3d190c3ad71 100644
--- a/editors/code/src/highlighting.ts
+++ b/editors/code/src/highlighting.ts
@@ -40,7 +40,7 @@ export function activateHighlighting(ctx: Ctx) {
         async (editor: vscode.TextEditor | undefined) => {
             if (!editor || editor.document.languageId !== 'rust') return;
             if (!ctx.config.highlightingOn) return;
-            let client = ctx.client;
+            const client = ctx.client;
             if (!client) return;
 
             const params: lc.TextDocumentIdentifier = {
@@ -106,7 +106,7 @@ class Highlighter {
     }
 
     public setHighlights(editor: vscode.TextEditor, highlights: Decoration[]) {
-        let client = this.ctx.client;
+        const client = this.ctx.client;
         if (!client) return;
         // Initialize decorations if necessary
         //
@@ -175,7 +175,7 @@ function initDecorations(): Map<string, vscode.TextEditorDecorationType> {
     const res = new Map();
     TAG_TO_SCOPES.forEach((scopes, tag) => {
         if (!scopes) throw `unmapped tag: ${tag}`;
-        let rule = theme.lookup(scopes);
+        const rule = theme.lookup(scopes);
         const decor = createDecorationFromTextmate(rule);
         res.set(tag, decor);
     });
diff --git a/editors/code/src/inlay_hints.ts b/editors/code/src/inlay_hints.ts
index 6357e44f1ef..ae75101831f 100644
--- a/editors/code/src/inlay_hints.ts
+++ b/editors/code/src/inlay_hints.ts
@@ -127,13 +127,13 @@ class HintsUpdater {
     }
 
     private async queryHints(documentUri: string): Promise<InlayHint[] | null> {
-        let client = this.ctx.client;
+        const client = this.ctx.client;
         if (!client) return null;
         const request: InlayHintsParams = {
             textDocument: { uri: documentUri },
         };
-        let tokenSource = new vscode.CancellationTokenSource();
-        let prev = this.pending.get(documentUri);
+        const tokenSource = new vscode.CancellationTokenSource();
+        const prev = this.pending.get(documentUri);
         if (prev) prev.cancel();
         this.pending.set(documentUri, tokenSource);
         try {
diff --git a/editors/code/tslint.json b/editors/code/tslint.json
index 318e02b4b3a..0df11b2f1bf 100644
--- a/editors/code/tslint.json
+++ b/editors/code/tslint.json
@@ -3,6 +3,7 @@
         "semicolon": [
             true,
             "always"
-        ]
+        ],
+        "prefer-const": true
     }
 }