diff --git a/kernel/int2f.asm b/kernel/int2f.asm
index f89295f..d73f1a0 100644
--- a/kernel/int2f.asm
+++ b/kernel/int2f.asm
@@ -63,7 +63,13 @@ Int2f3:
                 je      IntDosCal               ; Dos Internal calls
                 cmp     ax,4a02h
                 je      IntDosCal               ; Dos Internal calls
-                                        
+%ifdef WITHFAT32
+                cmp     ax,4a33h                ; Check DOS version 7
+                jne     Check4Share
+                xor     ax,ax                   ; no undocumented shell strings
+                iret
+Check4Share:
+%endif
                 cmp     ah,10h                  ; SHARE.EXE interrupt?
                 je      Int2f1                  ; yes, do installation check
                 cmp     ah,08h
diff --git a/mkfiles/generic.mak b/mkfiles/generic.mak
index 34a3ea0..f30bdc1 100644
--- a/mkfiles/generic.mak
+++ b/mkfiles/generic.mak
@@ -16,6 +16,7 @@ TARGETOPT=-3
 
 !if $(XFAT) == 32
 ALLCFLAGS=$(ALLCFLAGS) -DWITHFAT32
+NASMFLAGS=$(NASMFLAGS) -DWITHFAT32
 !endif
 
 NASM=$(XNASM)