diff --git a/reactos/dll/win32/kernel32/file/npipe.c b/reactos/dll/win32/kernel32/file/npipe.c
index ec68156f180..d62527e12a5 100644
--- a/reactos/dll/win32/kernel32/file/npipe.c
+++ b/reactos/dll/win32/kernel32/file/npipe.c
@@ -1069,7 +1069,7 @@ PeekNamedPipe(HANDLE hNamedPipe,
     NTSTATUS Status;
 
     /* Calculate the buffer space that we'll need and allocate it */
-    BufferSize = nBufferSize + FIELD_OFFSET(FILE_PIPE_PEEK_BUFFER, Data[0]);
+    BufferSize = nBufferSize + sizeof(FILE_PIPE_PEEK_BUFFER);
     Buffer = RtlAllocateHeap(RtlGetProcessHeap(), 0, BufferSize);
     if (Buffer == NULL)
     {