diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0d23ef962..aa869a58c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,6 +18,10 @@ Dates are in `YYYY-MM-DD` format and versions are in [semantic versioning](http:
 -   [#488](https://github.com/wordplaydev/wordplay/issues/488). Added animations off indicator on stage.
 -   [#500](https://github.com/wordplaydev/wordplay/issues/500). Improved explanation when there's a space between an evaluation's name and inputs.
 
+### Maintenance
+
+-   Upgraded to TypeScript 5.5.
+
 ## 0.10.1 2024-06-22
 
 ### Fixed
diff --git a/package-lock.json b/package-lock.json
index d82f09e03..b8618963c 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -51,7 +51,7 @@
                 "ts-json-schema-generator": "^1",
                 "tslib": "^2.6",
                 "tsx": "^4.7.0",
-                "typescript": "^5.4",
+                "typescript": "^5.5.2",
                 "vite": "^5.2.7",
                 "vite-plugin-eslint": "^1.8.1",
                 "vitest": "^1.4.0"
@@ -4367,9 +4367,9 @@
             "peer": true
         },
         "node_modules/colorjs.io": {
-            "version": "0.4.5",
-            "resolved": "https://registry.npmjs.org/colorjs.io/-/colorjs.io-0.4.5.tgz",
-            "integrity": "sha512-yCtUNCmge7llyfd/Wou19PMAcf5yC3XXhgFoAh6zsO2pGswhUPBaaUh8jzgHnXtXuZyFKzXZNAnyF5i+apICow=="
+            "version": "0.5.2",
+            "resolved": "https://registry.npmjs.org/colorjs.io/-/colorjs.io-0.5.2.tgz",
+            "integrity": "sha512-twmVoizEW7ylZSN32OgKdXRmo1qg+wT5/6C3xu5b9QsWzSFAhHLn2xd8ro0diCsKfCj1RdaTP/nrcW+vAoQPIw=="
         },
         "node_modules/combined-stream": {
             "version": "1.0.8",
@@ -10626,9 +10626,9 @@
             }
         },
         "node_modules/typescript": {
-            "version": "5.4.3",
-            "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.4.3.tgz",
-            "integrity": "sha512-KrPd3PKaCLr78MalgiwJnA25Nm8HAmdwN3mYUYZgG/wizIo9EainNVQI9/yDavtVFRN2h3k8uf3GLHuhDMgEHg==",
+            "version": "5.5.2",
+            "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.5.2.tgz",
+            "integrity": "sha512-NcRtPEOsPFFWjobJEtfihkLCZCXZt/os3zf8nTxjVH3RvTSxjrCamJpbExGvYOF+tFHc3pA65qpdwPbzjohhew==",
             "dev": true,
             "bin": {
                 "tsc": "bin/tsc",
diff --git a/package.json b/package.json
index 69e9f74c4..c9d9bf1ba 100644
--- a/package.json
+++ b/package.json
@@ -73,7 +73,7 @@
         "ts-json-schema-generator": "^1",
         "tslib": "^2.6",
         "tsx": "^4.7.0",
-        "typescript": "^5.4",
+        "typescript": "^5.5.2",
         "vite": "^5.2.7",
         "vite-plugin-eslint": "^1.8.1",
         "vitest": "^1.4.0"
@@ -81,7 +81,7 @@
     "type": "module",
     "dependencies": {
         "@axe-core/playwright": "^4.8.5",
-        "colorjs.io": "^0",
+        "colorjs.io": "^5.2",
         "decimal.js": "^10",
         "dexie": "^4.0",
         "firebase": "^10.11.0",
diff --git a/src/components/editor/Editor.svelte b/src/components/editor/Editor.svelte
index e53e156f7..c1f081c73 100644
--- a/src/components/editor/Editor.svelte
+++ b/src/components/editor/Editor.svelte
@@ -637,9 +637,8 @@
             spaceView instanceof HTMLElement && spaceView.dataset.id
                 ? parseInt(spaceView.dataset.id)
                 : undefined;
-        return tokenID
-            ? [source.getNodeByID(tokenID) as Token, spaceView]
-            : undefined;
+        const node = tokenID ? source.getNodeByID(tokenID) : undefined;
+        return node instanceof Token ? [node, spaceView] : undefined;
     }
 
     function getCaretPositionAt(event: PointerEvent): number | undefined {
diff --git a/src/nodes/Token.ts b/src/nodes/Token.ts
index 5d276dcf2..357faec28 100644
--- a/src/nodes/Token.ts
+++ b/src/nodes/Token.ts
@@ -52,7 +52,7 @@ export default class Token extends Node {
         return [];
     }
 
-    isLeaf() {
+    isLeaf(): this is Token {
         return true;
     }