diff --git a/src/display/fetch_stream.js b/src/display/fetch_stream.js
index 5cea226cf..37e15449c 100644
--- a/src/display/fetch_stream.js
+++ b/src/display/fetch_stream.js
@@ -35,7 +35,7 @@ function createFetchOptions(headers, withCredentials, abortController) {
   return {
     method: "GET",
     headers,
-    signal: abortController?.signal,
+    signal: abortController.signal,
     mode: "cors",
     credentials: withCredentials ? "include" : "same-origin",
     redirect: "follow",
@@ -114,9 +114,7 @@ class PDFFetchStreamReader {
       this._disableRange = true;
     }
 
-    if (typeof AbortController !== "undefined") {
-      this._abortController = new AbortController();
-    }
+    this._abortController = new AbortController();
     this._isStreamingSupported = !source.disableStream;
     this._isRangeSupported = !source.disableRange;
 
@@ -207,9 +205,7 @@ class PDFFetchStreamReader {
     if (this._reader) {
       this._reader.cancel(reason);
     }
-    if (this._abortController) {
-      this._abortController.abort();
-    }
+    this._abortController.abort();
   }
 }
 
@@ -224,10 +220,7 @@ class PDFFetchStreamRangeReader {
     this._readCapability = createPromiseCapability();
     this._isStreamingSupported = !source.disableStream;
 
-    if (typeof AbortController !== "undefined") {
-      this._abortController = new AbortController();
-    }
-
+    this._abortController = new AbortController();
     this._headers = createHeaders(this._stream.httpHeaders);
     this._headers.append("Range", `bytes=${begin}-${end - 1}`);
 
@@ -274,9 +267,7 @@ class PDFFetchStreamRangeReader {
     if (this._reader) {
       this._reader.cancel(reason);
     }
-    if (this._abortController) {
-      this._abortController.abort();
-    }
+    this._abortController.abort();
   }
 }