diff --git a/test/parallel/test-fs-promises-write-optional-params.js b/test/parallel/test-fs-promises-write-optional-params.js
index c87f6a35db08c3..4dd87155153769 100644
--- a/test/parallel/test-fs-promises-write-optional-params.js
+++ b/test/parallel/test-fs-promises-write-optional-params.js
@@ -54,6 +54,7 @@ async function testValid(dest, buffer, options) {
   assert.ok(writeResult.bytesWritten >= readResult.bytesRead);
   if (length !== undefined && length !== null) {
     assert.strictEqual(writeResult.bytesWritten, length);
+    assert.strictEqual(readResult.bytesRead, length);
   }
   if (offset === undefined || offset === 0) {
     assert.deepStrictEqual(writeBufCopy, readBufCopy);
diff --git a/test/parallel/test-fs-write-optional-params.js b/test/parallel/test-fs-write-optional-params.js
index c5660a18d6817c..11390ad42dbfd4 100644
--- a/test/parallel/test-fs-write-optional-params.js
+++ b/test/parallel/test-fs-write-optional-params.js
@@ -40,6 +40,7 @@ function testValidCb(buffer, options, index, callback) {
             assert.ok(bytesWritten >= bytesRead);
             if (length !== undefined && length !== null) {
               assert.strictEqual(bytesWritten, length);
+              assert.strictEqual(bytesRead, length);
             }
             if (offset === undefined || offset === 0) {
               assert.deepStrictEqual(writeBufCopy, readBufCopy);
diff --git a/test/parallel/test-fs-write-sync-optional-params.js b/test/parallel/test-fs-write-sync-optional-params.js
index bca19eddde28f9..ac2c501f682242 100644
--- a/test/parallel/test-fs-write-sync-optional-params.js
+++ b/test/parallel/test-fs-write-sync-optional-params.js
@@ -51,6 +51,7 @@ function testValid(dest, buffer, options) {
   assert.ok(bytesWritten >= bytesRead);
   if (length !== undefined && length !== null) {
     assert.strictEqual(bytesWritten, length);
+    assert.strictEqual(bytesRead, length);
   }
 }