diff --git a/hw/virtio/virtio-mem.c b/hw/virtio/virtio-mem.c
index ed170def48..e19ee817fe 100644
--- a/hw/virtio/virtio-mem.c
+++ b/hw/virtio/virtio-mem.c
@@ -235,7 +235,7 @@ static int virtio_mem_for_each_plugged_section(const VirtIOMEM *vmem,
     uint64_t offset, size;
     int ret = 0;
 
-    first_bit = s->offset_within_region / vmem->bitmap_size;
+    first_bit = s->offset_within_region / vmem->block_size;
     first_bit = find_next_bit(vmem->bitmap, vmem->bitmap_size, first_bit);
     while (first_bit < vmem->bitmap_size) {
         MemoryRegionSection tmp = *s;
@@ -267,7 +267,7 @@ static int virtio_mem_for_each_unplugged_section(const VirtIOMEM *vmem,
     uint64_t offset, size;
     int ret = 0;
 
-    first_bit = s->offset_within_region / vmem->bitmap_size;
+    first_bit = s->offset_within_region / vmem->block_size;
     first_bit = find_next_zero_bit(vmem->bitmap, vmem->bitmap_size, first_bit);
     while (first_bit < vmem->bitmap_size) {
         MemoryRegionSection tmp = *s;