diff --git a/package-lock.json b/package-lock.json
index 0dd0460f..fc168f4b 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -39,7 +39,7 @@
         "source-map": "0.6.1",
         "ts-jest": "24.3.0",
         "tsx": "4.19.2",
-        "typescript": "5.3.3",
+        "typescript": "5.9.3",
         "typescript-json-schema": "0.67.0",
         "uglify-es": "3.2.2",
         "uint8array-json-parser": "0.0.2"
@@ -10839,9 +10839,9 @@
       }
     },
     "node_modules/typescript": {
-      "version": "5.3.3",
-      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.3.3.tgz",
-      "integrity": "sha512-pXWcraxM0uxAS+tN0AG/BF2TyqmHO014Z070UsJ+pFvYuRSq8KH8DmWpnbXe0pEPDHXZV3FcAbJkijJ5oNEnWw==",
+      "version": "5.9.3",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.9.3.tgz",
+      "integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
       "dev": true,
       "license": "Apache-2.0",
       "bin": {
diff --git a/package.json b/package.json
index 0868b0c7..118cd4fa 100644
--- a/package.json
+++ b/package.json
@@ -54,7 +54,7 @@
     "source-map": "0.6.1",
     "ts-jest": "24.3.0",
     "tsx": "4.19.2",
-    "typescript": "5.3.3",
+    "typescript": "5.9.3",
     "typescript-json-schema": "0.67.0",
     "uglify-es": "3.2.2",
     "uint8array-json-parser": "0.0.2"
diff --git a/src/global.d.ts b/src/global.d.ts
deleted file mode 100644
index dc1f31bd..00000000
--- a/src/global.d.ts
+++ /dev/null
@@ -1,8 +0,0 @@
-declare global {
-  // Mock modern Typescript constructs used in JfrView until we update our Typescript
-  interface SymbolConstructor {
-    readonly dispose: symbol
-  }
-}
-
-export {}
diff --git a/src/import/index.ts b/src/import/index.ts
index 400166e7..a3e1eed9 100644
--- a/src/import/index.ts
+++ b/src/import/index.ts
@@ -38,7 +38,10 @@ export async function importProfileGroupFromBase64(
   b64contents: string,
 ): Promise<ProfileGroup | null> {
   return await importProfileGroup(
-    MaybeCompressedDataReader.fromArrayBuffer(fileName, decodeBase64(b64contents).buffer),
+    MaybeCompressedDataReader.fromArrayBuffer(
+      fileName,
+      decodeBase64(b64contents).buffer as ArrayBuffer,
+    ),
   )
 }
 
diff --git a/src/import/utils.ts b/src/import/utils.ts
index 9c78246e..cdbd6b8f 100644
--- a/src/import/utils.ts
+++ b/src/import/utils.ts
@@ -230,7 +230,7 @@ export class MaybeCompressedDataReader implements ProfileDataSource {
   ) {
     this.uncompressedData = maybeCompressedDataPromise.then(async (fileData: ArrayBuffer) => {
       try {
-        const result = pako.inflate(new Uint8Array(fileData)).buffer
+        const result = pako.inflate(new Uint8Array(fileData)).buffer as ArrayBuffer
         return result
       } catch (e) {
         return fileData
diff --git a/src/lib/utils.test.ts b/src/lib/utils.test.ts
index 5d02f5d8..aa6834ce 100644
--- a/src/lib/utils.test.ts
+++ b/src/lib/utils.test.ts
@@ -243,7 +243,7 @@ test('decodeBase64', () => {
 test('BufferBackedTextFileContent.firstChunk', async () => {
   await withMockedFileChunkSizeForTests(2, () => {
     const str = 'may\nyour\nrope\nbe\nlong'
-    const buffer = new TextEncoder().encode(str).buffer
+    const buffer = new TextEncoder().encode(str).buffer as ArrayBuffer
     const content = new BufferBackedTextFileContent(buffer)
     expect(content.firstChunk()).toEqual('ma')
   })
@@ -251,7 +251,7 @@ test('BufferBackedTextFileContent.firstChunk', async () => {
 
 test('BufferBackedTextFileContent.splitLines', async () => {
   function testWithString(str: string) {
-    const buffer = new TextEncoder().encode(str).buffer
+    const buffer = new TextEncoder().encode(str).buffer as ArrayBuffer
     const content = new BufferBackedTextFileContent(buffer)
     expect([...content.splitLines()]).toEqual(str.split('\n'))
   }
@@ -270,7 +270,7 @@ test('BufferBackedTextFileContent.parseAsJSON', async () => {
     // parseAsJSON is special cased to permissively allow trailing commas
     // and a mission closing bracket
     const str = '[200,300,400,'
-    const buffer = new TextEncoder().encode(str).buffer
+    const buffer = new TextEncoder().encode(str).buffer as ArrayBuffer
     const content = new BufferBackedTextFileContent(buffer)
 
     expect(content.parseAsJSON()).toEqual([200, 300, 400])
diff --git a/tsconfig.json b/tsconfig.json
index 69ec122f..9066b374 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -7,6 +7,7 @@
     "jsx": "react",
     "noUnusedLocals": true,
     "jsxFactory": "h",
-    "target": "es2015"
+    "target": "es2015",
+    "skipLibCheck": true
   }
 }