diff --git a/src/vs/workbench/services/hash/common/hashService.ts b/src/vs/workbench/services/hash/common/hashService.ts
index 88e8dfff5250ffd5460fe425113811b2b7c1de86..a8cbd8d9e6df787b45ef8189c9aa9a42f39308a0 100644
--- a/src/vs/workbench/services/hash/common/hashService.ts
+++ b/src/vs/workbench/services/hash/common/hashService.ts
@@ -23,10 +23,8 @@ export class HashService implements IHashService {
 
 	createSHA1(content: string): Thenable<string> {
 		return crypto.subtle.digest('SHA-1', new TextEncoder().encode(content)).then(buffer => {
-			const byteArray = new Uint8Array(buffer);
-
 			// https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto/digest#Converting_a_digest_to_a_hex_string
-			return [...byteArray].map(value => (`00${value.toString(16)}`).slice(-2)).join('');
+			return Array.prototype.map.call(new Uint8Array(buffer), value => `00${value.toString(16)}`.slice(-2)).join('');
 		});
 	}
 }