diff --git a/web/compatibility.js b/web/compatibility.js
index dd0edcf48..2ed06ac4b 100644
--- a/web/compatibility.js
+++ b/web/compatibility.js
@@ -85,6 +85,7 @@ if (typeof PDFJS === 'undefined') {
   }
 
   window.Uint8Array = TypedArray;
+  window.Int8Array = TypedArray;
 
   // we don't need support for set, byteLength for 32-bit array
   // so we can use the TypedArray as well