diff --git a/ds/bitmap.c b/ds/bitmap.c
index 01edc51..c1038f9 100644
--- a/ds/bitmap.c
+++ b/ds/bitmap.c
@@ -18,7 +18,7 @@ void bitmap_set(unsigned long *map, unsigned long bit)
 	unsigned long index = bit / BITS_PER_WORD;
 	unsigned long offset = (BITS_PER_WORD - bit - 1) & (BITS_PER_WORD - 1);
 	unsigned long mask = 1ul << offset;
-	
+
 	map[index] |= mask;
 }
 
@@ -27,18 +27,18 @@ void bitmap_clear(unsigned long *map, unsigned long bit)
 	unsigned long index = bit / BITS_PER_WORD;
 	unsigned long offset = bit & (BITS_PER_WORD - 1);
 	unsigned long mask = 1ul << offset;
-	
+
 	map[index] &= ~mask;
 }
 
 bool bitmap_check(unsigned long *map, unsigned long bit)
 {
 	unsigned long index = bit / BITS_PER_WORD;
-	unsigned long offset = bit & (BITS_PER_WORD - 1);
+	unsigned long offset = (BITS_PER_WORD - bit - 1) & (BITS_PER_WORD - 1);
 	unsigned long mask = 1ul << offset;
-	
+
 	return (map[index] & mask) != 0 ? true : false;
-	
+
 }
 
 unsigned int bitmap_count_set(unsigned long *map, unsigned long nbits)