=== modified file 'mysys/my_bitmap.c'
--- mysys/my_bitmap.c	2011-02-16 15:26:19 +0000
+++ mysys/my_bitmap.c	2011-05-18 18:09:57 +0000
@@ -301,7 +301,7 @@ void bitmap_set_prefix(MY_BITMAP *map, u
   m+= prefix_bytes;
   if ((prefix_bits= prefix_size & 7))
     *(m++)= (1 << prefix_bits)-1;
-  if ((d= no_bytes_in_map(map)-prefix_bytes))
+  if ((d= no_bytes_in_map(map) - (m - (uchar *) map->bitmap)))
     bzero(m, d);
 }
 

=== modified file 'sql/sql_bitmap.h'
--- sql/sql_bitmap.h	2008-01-29 11:14:34 +0000
+++ sql/sql_bitmap.h	2011-05-18 18:13:05 +0000
@@ -47,7 +47,11 @@ template <uint default_width> class Bitm
   void intersect(ulonglong map2buff)
   {
     MY_BITMAP map2;
-    bitmap_init(&map2, (uint32 *)&map2buff, sizeof(ulonglong)*8, 0);
+    ulonglong buf;
+
+    /* bitmap_init() initializes the supplied buffer */
+    bitmap_init(&map2, (uint32 *) &buf, sizeof(ulonglong) * 8, 0);
+    buf= map2buff;
     bitmap_intersect(&map, &map2);
   }
   /* Use highest bit for all bits above sizeof(ulonglong)*8. */
@@ -87,9 +91,9 @@ template <uint default_width> class Bitm
   ulonglong to_ulonglong() const
   {
     if (sizeof(buffer) >= 8)
-      return uint8korr(buffer);
+      return uint8korr((uchar *) buffer);
     DBUG_ASSERT(sizeof(buffer) >= 4);
-    return (ulonglong) uint4korr(buffer);
+    return (ulonglong) uint4korr((uchar *) buffer);
   }
 };