diff --git a/lib/buffer.js b/lib/buffer.js
index 398357c6845568..43d9d4d5822bd7 100644
--- a/lib/buffer.js
+++ b/lib/buffer.js
@@ -278,7 +278,8 @@ function assertSize(size) {
 Buffer.alloc = function alloc(size, fill, encoding) {
   assertSize(size);
   if (fill !== undefined && fill !== 0 && size > 0) {
-    return _fill(createUnsafeBuffer(size), fill, encoding);
+    const buf = createUnsafeBuffer(size);
+    return _fill(buf, fill, 0, buf.length, encoding);
   }
   return new FastBuffer(size);
 };
diff --git a/test/parallel/test-buffer-alloc.js b/test/parallel/test-buffer-alloc.js
index daab9c9edc12e9..f89e25fdbb2f92 100644
--- a/test/parallel/test-buffer-alloc.js
+++ b/test/parallel/test-buffer-alloc.js
@@ -1039,3 +1039,10 @@ common.expectsError(() => {
   code: 'ERR_INVALID_ARG_VALUE',
   type: TypeError
 });
+
+common.expectsError(() => {
+  Buffer.alloc(40, 'x', 20);
+}, {
+  code: 'ERR_INVALID_ARG_TYPE',
+  type: TypeError
+});