diff --git a/reactos/lib/fslib/vfatlib/fat12.c b/reactos/lib/fslib/vfatlib/fat12.c
index 2e7d9b696e8..58725223777 100644
--- a/reactos/lib/fslib/vfatlib/fat12.c
+++ b/reactos/lib/fslib/vfatlib/fat12.c
@@ -62,12 +62,12 @@ Fat12WriteBootSector(IN HANDLE FileHandle,
     /* Allocate buffer for new bootsector */
     NewBootSector = (PUCHAR)RtlAllocateHeap(RtlGetProcessHeap (),
                                             0,
-                                            SECTORSIZE);
+                                            BootSector->BytesPerSector);
     if (NewBootSector == NULL)
         return STATUS_INSUFFICIENT_RESOURCES;
 
     /* Zero the new bootsector */
-    memset(NewBootSector, 0, SECTORSIZE);
+    memset(NewBootSector, 0, BootSector->BytesPerSector);
 
     /* Copy FAT16 BPB to new bootsector */
     memcpy((NewBootSector + 3),
@@ -82,7 +82,7 @@ Fat12WriteBootSector(IN HANDLE FileHandle,
                          NULL,
                          &IoStatusBlock,
                          NewBootSector,
-                         SECTORSIZE,
+                         BootSector->BytesPerSector,
                          &FileOffset,
                          NULL);
     if (!NT_SUCCESS(Status))
diff --git a/reactos/lib/fslib/vfatlib/fat16.c b/reactos/lib/fslib/vfatlib/fat16.c
index 384c01194dd..1194de905e7 100644
--- a/reactos/lib/fslib/vfatlib/fat16.c
+++ b/reactos/lib/fslib/vfatlib/fat16.c
@@ -62,12 +62,12 @@ Fat16WriteBootSector(IN HANDLE FileHandle,
     /* Allocate buffer for new bootsector */
     NewBootSector = (PUCHAR)RtlAllocateHeap(RtlGetProcessHeap(),
                                             0,
-                                            SECTORSIZE);
+                                            BootSector->BytesPerSector);
     if (NewBootSector == NULL)
         return STATUS_INSUFFICIENT_RESOURCES;
 
     /* Zero the new bootsector */
-    memset(NewBootSector, 0, SECTORSIZE);
+    memset(NewBootSector, 0, BootSector->BytesPerSector);
 
     /* Copy FAT16 BPB to new bootsector */
     memcpy((NewBootSector + 3),
@@ -82,7 +82,7 @@ Fat16WriteBootSector(IN HANDLE FileHandle,
                          NULL,
                          &IoStatusBlock,
                          NewBootSector,
-                         SECTORSIZE,
+                         BootSector->BytesPerSector,
                          &FileOffset,
                          NULL);
     if (!NT_SUCCESS(Status))
diff --git a/reactos/lib/fslib/vfatlib/fat32.c b/reactos/lib/fslib/vfatlib/fat32.c
index c0e93c842cf..9be3e050b12 100644
--- a/reactos/lib/fslib/vfatlib/fat32.c
+++ b/reactos/lib/fslib/vfatlib/fat32.c
@@ -62,12 +62,12 @@ Fat32WriteBootSector(IN HANDLE FileHandle,
     /* Allocate buffer for new bootsector */
     NewBootSector = (PUCHAR)RtlAllocateHeap(RtlGetProcessHeap(),
                                             0,
-                                            SECTORSIZE);
+                                            BootSector->BytesPerSector);
     if (NewBootSector == NULL)
         return STATUS_INSUFFICIENT_RESOURCES;
 
     /* Zero the new bootsector */
-    memset(NewBootSector, 0, SECTORSIZE);
+    memset(NewBootSector, 0, BootSector->BytesPerSector);
 
     /* Copy FAT32 BPB to new bootsector */
     memcpy((NewBootSector + 3),
@@ -82,7 +82,7 @@ Fat32WriteBootSector(IN HANDLE FileHandle,
                          NULL,
                          &IoStatusBlock,
                          NewBootSector,
-                         SECTORSIZE,
+                         BootSector->BytesPerSector,
                          &FileOffset,
                          NULL);
     if (!NT_SUCCESS(Status))
@@ -97,14 +97,14 @@ Fat32WriteBootSector(IN HANDLE FileHandle,
     /* Write backup boot sector */
     if (BootSector->BootBackup != 0x0000)
     {
-        FileOffset.QuadPart = (ULONGLONG)((ULONG) BootSector->BootBackup * SECTORSIZE);
+        FileOffset.QuadPart = (ULONGLONG)((ULONG)BootSector->BootBackup * BootSector->BytesPerSector);
         Status = NtWriteFile(FileHandle,
                              NULL,
                              NULL,
                              NULL,
                              &IoStatusBlock,
                              NewBootSector,
-                             SECTORSIZE,
+                             BootSector->BytesPerSector,
                              &FileOffset,
                              NULL);
         if (!NT_SUCCESS(Status))
diff --git a/reactos/lib/fslib/vfatlib/vfatlib.c b/reactos/lib/fslib/vfatlib/vfatlib.c
index 9537b9b5b11..58738e68f54 100755
--- a/reactos/lib/fslib/vfatlib/vfatlib.c
+++ b/reactos/lib/fslib/vfatlib/vfatlib.c
@@ -143,9 +143,9 @@ VfatFormat(IN PUNICODE_STRING DriveRoot,
         Callback (PROGRESS, 0, (PVOID)&Context.Percent);
     }
 
-    if (PartitionInfo.PartitionLength.QuadPart < (4200LL * 1024LL))
+    if (PartitionInfo.PartitionType == PARTITION_FAT_12)
     {
-        /* FAT12 (volume is smaller than 4.1MB) */
+        /* FAT12 */
         Status = Fat12Format(FileHandle,
                              &PartitionInfo,
                              &DiskGeometry,
@@ -154,9 +154,11 @@ VfatFormat(IN PUNICODE_STRING DriveRoot,
                              ClusterSize,
                              &Context);
     }
-    else if (PartitionInfo.PartitionLength.QuadPart < (512LL * 1024LL * 1024LL))
+    else if (PartitionInfo.PartitionType == PARTITION_FAT_16 ||
+             PartitionInfo.PartitionType == PARTITION_HUGE ||
+             PartitionInfo.PartitionType == PARTITION_XINT13)
     {
-        /* FAT16 (volume is smaller than 512MB) */
+        /* FAT16 */
         Status = Fat16Format(FileHandle,
                              &PartitionInfo,
                              &DiskGeometry,
@@ -165,16 +167,21 @@ VfatFormat(IN PUNICODE_STRING DriveRoot,
                              ClusterSize,
                              &Context);
     }
+    else if (PartitionInfo.PartitionType == PARTITION_FAT32 ||
+             PartitionInfo.PartitionType == PARTITION_FAT32_XINT13)
+    {
+        /* FAT32 */
+        Status = Fat32Format(FileHandle,
+                             &PartitionInfo,
+                             &DiskGeometry,
+                             Label,
+                             QuickFormat,
+                             ClusterSize,
+                             &Context);
+    }
     else
     {
-        /* FAT32 (volume is 512MB or larger) */
-        Status = Fat32Format(FileHandle,
-                             &PartitionInfo,
-                             &DiskGeometry,
-                             Label,
-                             QuickFormat,
-                             ClusterSize,
-                             &Context);
+        Status = STATUS_INVALID_PARAMETER;
     }
 
     NtClose(FileHandle);
diff --git a/reactos/lib/fslib/vfatlib/vfatlib.h b/reactos/lib/fslib/vfatlib/vfatlib.h
index 6ae54e63163..8e96ca574ec 100755
--- a/reactos/lib/fslib/vfatlib/vfatlib.h
+++ b/reactos/lib/fslib/vfatlib/vfatlib.h
@@ -19,8 +19,6 @@
 #include "check/file.h"
 #include "check/check.h"
 
-#define SECTORSIZE 512
-
 #include <pshpack1.h>
 typedef struct _FAT16_BOOT_SECTOR
 {