diff --git a/include/fat32/fat32_structures.inc b/include/fat32/fat32_structures.inc
index 0ca5107..3f8ccfb 100755
--- a/include/fat32/fat32_structures.inc
+++ b/include/fat32/fat32_structures.inc
@@ -65,11 +65,11 @@ struc FAT32_bpb_t
     .u16_RootEntryCount16    resw 1      ; Root dir entry count field, 0 on fat32
     .u16_TotalSectors16      resw 1      ; total number of sectors size, 0 on fat32
     .u8_MediaDesc            resb 1
-    .u16_FatSize16           resw 1      ; FAT size 16, 0 on fat32
+    .u16_FATSize16           resw 1      ; FAT size 16, 0 on fat32
     .u16_SectorsPerTrack     resw 1
     .u16_HeadCount           resw 1
     .u32_HiddenSectors       resd 1
-    .u32_TotalSectors        resd 1
+    .u32_TotalSectors32      resd 1
 endstruc
 
 ; EBPB Information (FAT32)
@@ -89,7 +89,7 @@ endstruc
 ;   8 	System identifier string. Always "FAT32   ". The spec says never to trust the contents of this string for any use.
 
 struc FAT32_ebpb_t
-    .u32_FATSz             resd 1      ; size of *each* fat in sectors, total = FATSz * (# of FATs)
+    .u32_FATSize32         resd 1      ; size of *each* fat in sectors, total = FATSz * (# of FATs)
     .u16_ExtFlags          resw 1
     .u16_FSVersion         resw 1
     .u32_RootDirCluster    resd 1
diff --git a/src/stage2/stage2.nasm b/src/stage2/stage2.nasm
index 62e5dbb..a5dd3d5 100755
--- a/src/stage2/stage2.nasm
+++ b/src/stage2/stage2.nasm
@@ -257,8 +257,15 @@ ReadVbrData:
     mov bx, [bp + 6]
     cmp word [bx + 0x1FE], 0xAA55           ; check for bytes at end
     jne ReadVbrData.error_nosign
-.check_FAT_size:
-    test word [bx + FAT32_bpb_t.u16_TotalSectors16], 0      ; TotSectors16 will not be set if FAT32
+.check_FAT_sanity:
+    ; we only quickly validate that this is *probably* a FAT32 volume
+    test word [bx + FAT32_bpb_t.u16_TotalSectors16], 0      ; TotalSectors16 should be 0 (use TotalSectors32 in bpb)
+    jnz ReadVbrData.error_badfatfs
+
+    test word [bx + FAT32_bpb_t.u16_FATSize16], 0           ; FatSize16 will be 0 if FAT32 (use FATSize32 in ebpb)
+    jnz ReadVbrData.error_badfatfs
+
+    test word [bx + FAT32_bpb_t.u16_RootEntryCount16], 0    ; root dir info is in data clusters on fat32
     jnz ReadVbrData.error_badfatfs
 .endp:
     __CDECL16_PROC_EXIT