diff --git a/package-lock.json b/package-lock.json
index c1ef78f37..3c90e6d8f 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -58,7 +58,7 @@
         "sync-monorepo-packages": "1.0.2",
         "ts-node": "10.9.2",
         "tsd": "0.31.2",
-        "typescript": "5.5.4",
+        "typescript": "5.6.2",
         "validate.js": "0.13.1",
         "webdriverio": "8.40.5",
         "ws": "8.18.0",
@@ -17633,9 +17633,9 @@
       "license": "MIT"
     },
     "node_modules/typescript": {
-      "version": "5.5.4",
-      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.5.4.tgz",
-      "integrity": "sha512-Mtq29sKDAEYP7aljRgtPOpTvOfbwRWlS6dPRzwjdE+C0R4brX/GUyhHSecbHMFLNBLcJIPt9nl9yG5TZ1weH+Q==",
+      "version": "5.6.2",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.6.2.tgz",
+      "integrity": "sha512-NW8ByodCSNCwZeghjN3o+JX5OFH0Ojg6sadjEKY4huZ52TqbJTJnDo5+Tw98lSy63NZvi4n+ez5m2u5d4PkZyw==",
       "license": "Apache-2.0",
       "bin": {
         "tsc": "bin/tsc",
@@ -19664,7 +19664,7 @@
         "source-map-support": "0.5.21",
         "teen_process": "2.2.0",
         "type-fest": "4.26.1",
-        "typescript": "5.5.4",
+        "typescript": "5.6.2",
         "yaml": "2.5.1",
         "yargs": "17.7.2",
         "yargs-parser": "21.1.1"
@@ -20808,7 +20808,7 @@
         "source-map-support": "0.5.21",
         "teen_process": "2.2.0",
         "type-fest": "4.26.1",
-        "typescript": "5.5.4",
+        "typescript": "5.6.2",
         "yaml": "2.5.1",
         "yargs": "17.7.2",
         "yargs-parser": "21.1.1"
@@ -33241,9 +33241,9 @@
       "dev": true
     },
     "typescript": {
-      "version": "5.5.4",
-      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.5.4.tgz",
-      "integrity": "sha512-Mtq29sKDAEYP7aljRgtPOpTvOfbwRWlS6dPRzwjdE+C0R4brX/GUyhHSecbHMFLNBLcJIPt9nl9yG5TZ1weH+Q=="
+      "version": "5.6.2",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.6.2.tgz",
+      "integrity": "sha512-NW8ByodCSNCwZeghjN3o+JX5OFH0Ojg6sadjEKY4huZ52TqbJTJnDo5+Tw98lSy63NZvi4n+ez5m2u5d4PkZyw=="
     },
     "ua-parser-js": {
       "version": "1.0.33",
diff --git a/package.json b/package.json
index 6d2afa71c..83beb714a 100644
--- a/package.json
+++ b/package.json
@@ -128,7 +128,7 @@
     "sync-monorepo-packages": "1.0.2",
     "ts-node": "10.9.2",
     "tsd": "0.31.2",
-    "typescript": "5.5.4",
+    "typescript": "5.6.2",
     "validate.js": "0.13.1",
     "webdriverio": "8.40.5",
     "ws": "8.18.0",
diff --git a/packages/docutils/lib/fs.ts b/packages/docutils/lib/fs.ts
index b44289757..52c88ba7e 100644
--- a/packages/docutils/lib/fs.ts
+++ b/packages/docutils/lib/fs.ts
@@ -167,10 +167,12 @@ export function safeWriteFile(filepath: string, content: JsonValue, overwrite =
   });
 }
 
+type WhichFunction = (cmd: string, opts?: {nothrow: boolean}) => Promise<string|null>;
+
 /**
  * `which` with memoization
  */
-const cachedWhich = _.memoize(fs.which as typeof import('which'));
+const cachedWhich = _.memoize(fs.which as WhichFunction);
 
 /**
  * Finds `npm` executable
@@ -220,7 +222,7 @@ export const findMike = _.partial(async () => {
  * `python3` is preferred over `python`, since the latter could be Python 2.
  */
 export const findPython = _.memoize(
-  async (): Promise<string | undefined> => (await whichPython3()) ?? (await whichPython()),
+  async (): Promise<string | null> => (await whichPython3()) ?? (await whichPython()),
 );
 
 /**
diff --git a/packages/docutils/package.json b/packages/docutils/package.json
index 4746313ac..9b248531c 100644
--- a/packages/docutils/package.json
+++ b/packages/docutils/package.json
@@ -64,7 +64,7 @@
     "source-map-support": "0.5.21",
     "teen_process": "2.2.0",
     "type-fest": "4.26.1",
-    "typescript": "5.5.4",
+    "typescript": "5.6.2",
     "yaml": "2.5.1",
     "yargs": "17.7.2",
     "yargs-parser": "21.1.1"