diff --git a/rootdir/init.rc b/rootdir/init.rc
index f00479e..58f0495 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -54,6 +54,10 @@
     mkdir /linkerconfig/bootstrap 0755
     mkdir /linkerconfig/default 0755
 
+    # Greatly extend dm-verity's Merkle tree cache timeout.  The default timeout
+    # is much too short and is unnecessary, given that there is also a shrinker.
+    write /sys/module/dm_bufio/parameters/max_age_seconds 86400
+
     # Disable dm-verity hash prefetching, since it doesn't help performance
     # Read more in b/136247322
     write /sys/module/dm_verity/parameters/prefetch_cluster 0