diff --git a/block/vhdx.c b/block/vhdx.c
index 1e7e03ebed..9a51428317 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -264,10 +264,10 @@ static void vhdx_region_unregister_all(BDRVVHDXState *s)
 
 static void vhdx_set_shift_bits(BDRVVHDXState *s)
 {
-    s->logical_sector_size_bits = 31 - clz32(s->logical_sector_size);
-    s->sectors_per_block_bits =   31 - clz32(s->sectors_per_block);
-    s->chunk_ratio_bits =         63 - clz64(s->chunk_ratio);
-    s->block_size_bits =          31 - clz32(s->block_size);
+    s->logical_sector_size_bits = ctz32(s->logical_sector_size);
+    s->sectors_per_block_bits =   ctz32(s->sectors_per_block);
+    s->chunk_ratio_bits =         ctz64(s->chunk_ratio);
+    s->block_size_bits =          ctz32(s->block_size);
 }
 
 /*