diff --git a/block.c b/block.c
index 5db266be2103a1c6db107600f26afd39abd05a08..ceaca44975eaf660ccd82cb0201a02316a23197e 100644
--- a/block.c
+++ b/block.c
@@ -3313,11 +3313,7 @@ int bdrv_truncate(BdrvChild *child, int64_t offset)
     BlockDriver *drv = bs->drv;
     int ret;
 
-    /* FIXME: Some format block drivers use this function instead of implicitly
-     *        growing their file by writing beyond its end.
-     *        See bdrv_aligned_pwritev() for an explanation why we currently
-     *        cannot assert this permission in that case. */
-    // assert(child->perm & BLK_PERM_RESIZE);
+    assert(child->perm & BLK_PERM_RESIZE);
 
     if (!drv)
         return -ENOMEDIUM;
diff --git a/block/io.c b/block/io.c
index a7142e00e833fcb6f752c32b9bbd3f0a26956e89..a32fd1d9e59248a741db5ae97df74d55fa0a9d61 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1362,16 +1362,8 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChild *child,
     assert(!waited || !req->serialising);
     assert(req->overlap_offset <= offset);
     assert(offset + bytes <= req->overlap_offset + req->overlap_bytes);
-    /* FIXME: Block migration uses the BlockBackend of the guest device at a
-     *        point when it has not yet taken write permissions. This will be
-     *        fixed by a future patch, but for now we have to bypass this
-     *        assertion for block migration to work. */
-    // assert(child->perm & BLK_PERM_WRITE);
-    /* FIXME: Because of the above, we also cannot guarantee that all format
-     *        BDS take the BLK_PERM_RESIZE permission on their file BDS, since
-     *        they are not obligated to do so if they do not have any parent
-     *        that has taken the permission to write to them. */
-    // assert(end_sector <= bs->total_sectors || child->perm & BLK_PERM_RESIZE);
+    assert(child->perm & BLK_PERM_WRITE);
+    assert(end_sector <= bs->total_sectors || child->perm & BLK_PERM_RESIZE);
 
     ret = notifier_with_return_list_notify(&bs->before_write_notifiers, req);