diff --git a/benchmark/fs/readfile-partitioned.js b/benchmark/fs/readfile-partitioned.js
index fac331ec38ba82..e0ca7a2c1bbdbe 100644
--- a/benchmark/fs/readfile-partitioned.js
+++ b/benchmark/fs/readfile-partitioned.js
@@ -17,12 +17,13 @@ const zlib = require('zlib');
 const assert = require('assert');
 
 const bench = common.createBenchmark(main, {
-  dur: [5],
+  duration: [5],
+  encoding: ['', 'utf-8'],
   len: [1024, 16 * 1024 * 1024],
   concurrent: [1, 10]
 });
 
-function main({ len, dur, concurrent }) {
+function main({ len, duration, concurrent, encoding }) {
   try {
     fs.unlinkSync(filename);
   } catch {
@@ -47,10 +48,10 @@ function main({ len, dur, concurrent }) {
     } catch {
       // Continue regardless of error.
     }
-  }, dur * 1000);
+  }, duration * 1000);
 
   function read() {
-    fs.readFile(filename, afterRead);
+    fs.readFile(filename, encoding, afterRead);
   }
 
   function afterRead(er, data) {
diff --git a/benchmark/fs/readfile-promises.js b/benchmark/fs/readfile-promises.js
index 5cfa5b4cc02465..0fa92fdffad78d 100644
--- a/benchmark/fs/readfile-promises.js
+++ b/benchmark/fs/readfile-promises.js
@@ -15,11 +15,12 @@ const filename = path.resolve(tmpdir.path,
 
 const bench = common.createBenchmark(main, {
   duration: [5],
+  encoding: ['', 'utf-8'],
   len: [1024, 16 * 1024 * 1024],
   concurrent: [1, 10]
 });
 
-function main({ len, duration, concurrent }) {
+function main({ len, duration, concurrent, encoding }) {
   try {
     fs.unlinkSync(filename);
   } catch {
@@ -44,7 +45,7 @@ function main({ len, duration, concurrent }) {
   }, duration * 1000);
 
   function read() {
-    fs.promises.readFile(filename)
+    fs.promises.readFile(filename, encoding)
       .then((res) => afterRead(undefined, res))
       .catch((err) => afterRead(err));
   }
diff --git a/benchmark/fs/readfile.js b/benchmark/fs/readfile.js
index e27fe08f43ca86..575ceff34eb294 100644
--- a/benchmark/fs/readfile.js
+++ b/benchmark/fs/readfile.js
@@ -15,11 +15,12 @@ const filename = path.resolve(tmpdir.path,
 
 const bench = common.createBenchmark(main, {
   duration: [5],
+  encoding: ['', 'utf-8'],
   len: [1024, 16 * 1024 * 1024],
   concurrent: [1, 10]
 });
 
-function main({ len, duration, concurrent }) {
+function main({ len, duration, concurrent, encoding }) {
   try {
     fs.unlinkSync(filename);
   } catch {
@@ -44,7 +45,7 @@ function main({ len, duration, concurrent }) {
   }, duration * 1000);
 
   function read() {
-    fs.readFile(filename, afterRead);
+    fs.readFile(filename, encoding, afterRead);
   }
 
   function afterRead(er, data) {