diff --git a/lib/internal/test_runner/runner.js b/lib/internal/test_runner/runner.js
index e08e638cf9bb..e6d82bf431df 100644
--- a/lib/internal/test_runner/runner.js
+++ b/lib/internal/test_runner/runner.js
@@ -331,12 +331,12 @@ class FileTest extends Test {
     while (bufferHead?.length >= kSerializedSizeHeader) {
       // We call `readUInt32BE` manually here, because this is faster than first converting
       // it to a buffer and using `readUInt32BE` on that.
-      const fullMessageSize = (
+      const fullMessageSize = ((
         bufferHead[kV8HeaderLength] << 24 |
         bufferHead[kV8HeaderLength + 1] << 16 |
         bufferHead[kV8HeaderLength + 2] << 8 |
         bufferHead[kV8HeaderLength + 3]
-      ) + kSerializedSizeHeader;
+      ) >>> 0) + kSerializedSizeHeader;
 
       if (this.#rawBufferSize < fullMessageSize) break;