diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index c9b8a6fd5201cd7a3bfc6cdcbc89f9a99ddb2363..6c8761e0275e5cc7a59c1740133c63a901dc8b85 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -798,12 +798,23 @@ void bdrv_merge_dirty_bitmap(BdrvDirtyBitmap *dest, const BdrvDirtyBitmap *src,
 
     qemu_mutex_lock(dest->mutex);
 
-    assert(bdrv_dirty_bitmap_enabled(dest));
-    assert(!bdrv_dirty_bitmap_readonly(dest));
+    if (bdrv_dirty_bitmap_frozen(dest)) {
+        error_setg(errp, "Bitmap '%s' is frozen and cannot be modified",
+                   dest->name);
+        goto out;
+    }
+
+    if (bdrv_dirty_bitmap_readonly(dest)) {
+        error_setg(errp, "Bitmap '%s' is readonly and cannot be modified",
+                   dest->name);
+        goto out;
+    }
 
     if (!hbitmap_merge(dest->bitmap, src->bitmap)) {
         error_setg(errp, "Bitmaps are incompatible and can't be merged");
+        goto out;
     }
 
+out:
     qemu_mutex_unlock(dest->mutex);
 }
diff --git a/blockdev.c b/blockdev.c
index 1869f9aaf308f41fe2cbc312374b4f76cff0fea3..e3398e141ae43b6c6900b81b2c280fc4fb843158 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2962,16 +2962,6 @@ void qmp_x_block_dirty_bitmap_merge(const char *node, const char *dst_name,
         return;
     }
 
-    if (bdrv_dirty_bitmap_frozen(dst)) {
-        error_setg(errp, "Bitmap '%s' is frozen and cannot be modified",
-                   dst_name);
-        return;
-    } else if (bdrv_dirty_bitmap_readonly(dst)) {
-        error_setg(errp, "Bitmap '%s' is readonly and cannot be modified",
-                   dst_name);
-        return;
-    }
-
     src = bdrv_find_dirty_bitmap(bs, src_name);
     if (!src) {
         error_setg(errp, "Dirty bitmap '%s' not found", src_name);