diff --git a/lib/internal/fs/promises.js b/lib/internal/fs/promises.js
index 86e6924ca2104e..4b568b52b8d106 100644
--- a/lib/internal/fs/promises.js
+++ b/lib/internal/fs/promises.js
@@ -315,23 +315,24 @@ async function readFileHandle(filehandle, options) {
     throw new ERR_FS_FILE_TOO_LARGE(size);
 
   const chunks = [];
-  const chunkSize = size === 0 ?
-    kReadFileMaxChunkSize :
-    MathMin(size, kReadFileMaxChunkSize);
+  let isFirstChunk = true;
+  const firstChunkSize = size === 0 ? kReadFileMaxChunkSize : size;
+  const chunkSize = MathMin(firstChunkSize, kReadFileMaxChunkSize);
   let endOfFile = false;
   do {
     if (signal?.aborted) {
       throw lazyDOMException('The operation was aborted', 'AbortError');
     }
-    const buf = Buffer.alloc(chunkSize);
+    const buf = Buffer.alloc(isFirstChunk ? firstChunkSize : chunkSize);
     const { bytesRead, buffer } =
-      await read(filehandle, buf, 0, chunkSize, -1);
+      await read(filehandle, buf, 0, buf.length, -1);
     endOfFile = bytesRead === 0;
     if (bytesRead > 0)
       ArrayPrototypePush(chunks, buffer.slice(0, bytesRead));
+    isFirstChunk = false;
   } while (!endOfFile);
 
-  const result = Buffer.concat(chunks);
+  const result = chunks.length === 1 ? chunks[0] : Buffer.concat(chunks);
 
   return options.encoding ? result.toString(options.encoding) : result;
 }