diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index a04c6e4154..df0110cf9f 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -455,7 +455,7 @@ uint32_t bdrv_get_default_bitmap_granularity(BlockDriverState *bs)
     return granularity;
 }
 
-uint32_t bdrv_dirty_bitmap_granularity(BdrvDirtyBitmap *bitmap)
+uint32_t bdrv_dirty_bitmap_granularity(const BdrvDirtyBitmap *bitmap)
 {
     return BDRV_SECTOR_SIZE << hbitmap_granularity(bitmap->bitmap);
 }
diff --git a/include/block/dirty-bitmap.h b/include/block/dirty-bitmap.h
index ad6558af56..ab89f08e3d 100644
--- a/include/block/dirty-bitmap.h
+++ b/include/block/dirty-bitmap.h
@@ -29,7 +29,7 @@ void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap);
 void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap);
 BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs);
 uint32_t bdrv_get_default_bitmap_granularity(BlockDriverState *bs);
-uint32_t bdrv_dirty_bitmap_granularity(BdrvDirtyBitmap *bitmap);
+uint32_t bdrv_dirty_bitmap_granularity(const BdrvDirtyBitmap *bitmap);
 uint32_t bdrv_dirty_bitmap_meta_granularity(BdrvDirtyBitmap *bitmap);
 bool bdrv_dirty_bitmap_enabled(BdrvDirtyBitmap *bitmap);
 bool bdrv_dirty_bitmap_frozen(BdrvDirtyBitmap *bitmap);