diff --git a/minivhd_internal.h b/minivhd_internal.h
index fca2fda..dd4bb19 100644
--- a/minivhd_internal.h
+++ b/minivhd_internal.h
@@ -6,9 +6,9 @@
 /* The following bit array macros adapted from 
    http://www.mathcs.emory.edu/~cheung/Courses/255/Syllabus/1-C-intro/bit-array.html */
 
-#define VHD_SETBIT(A,k)     ( A[(k/8)] |= (1 << (k%8)) )
-#define VHD_CLEARBIT(A,k)   ( A[(k/8)] &= ~(1 << (k%8)) )
-#define VHD_TESTBIT(A,k)    ( A[(k/8)] & (1 << (k%8)) )
+#define VHD_SETBIT(A,k)     ( A[(k/8)] |= (0x80 >> (k%8)) )
+#define VHD_CLEARBIT(A,k)   ( A[(k/8)] &= ~(0x80 >> (k%8)) )
+#define VHD_TESTBIT(A,k)    ( A[(k/8)] & (0x80 >> (k%8)) )
 
 extern uint8_t VFT_CONECTIX_COOKIE[];
 extern uint8_t VFT_CREATOR[];