diff --git a/reactos/base/setup/usetup/partlist.c b/reactos/base/setup/usetup/partlist.c
index 3fc799af1c7..7e2c7510976 100644
--- a/reactos/base/setup/usetup/partlist.c
+++ b/reactos/base/setup/usetup/partlist.c
@@ -701,6 +701,7 @@ AddDiskToList (HANDLE FileHandle,
   ULONG i;
   PLIST_ENTRY ListEntry;
   PBIOSDISKENTRY BiosDiskEntry;
+  ULONG LayoutBufferSize;
 
   Status = NtDeviceIoControlFile (FileHandle,
                                   NULL,
@@ -870,9 +871,15 @@ AddDiskToList (HANDLE FileHandle,
 
   InsertAscendingList(&List->DiskListHead, DiskEntry, DISKENTRY, ListEntry, BiosDiskNumber);
 
+  /*
+   * Allocate a buffer for 26 logical drives (2 entries each == 52) 
+   * plus the main partiton table (4 entries). Total 56 entries.
+   */
+  LayoutBufferSize = sizeof(DRIVE_LAYOUT_INFORMATION) +
+                     ((56 - ANYSIZE_ARRAY) * sizeof(PARTITION_INFORMATION));
   LayoutBuffer = (DRIVE_LAYOUT_INFORMATION*)RtlAllocateHeap (ProcessHeap,
                   0,
-                  8192);
+                  LayoutBufferSize);
   if (LayoutBuffer == NULL)
   {
     return;
@@ -887,7 +894,7 @@ AddDiskToList (HANDLE FileHandle,
                                   NULL,
                                   0,
                                   LayoutBuffer,
-                                  8192);
+                                  LayoutBufferSize);
   if (NT_SUCCESS (Status))
   {
     if (LayoutBuffer->PartitionCount == 0)