diff --git a/lagarto-ox.nix b/lagarto-ox.nix
index 175649a..1a1e4e6 100644
--- a/lagarto-ox.nix
+++ b/lagarto-ox.nix
@@ -91,16 +91,17 @@
       # dead. Monitor from the host with:
       # while [ 1 ]; do xxd -s $((0x1bfff0000 - 0x60000000)) \
       #   -l 4 /dev/qdma34000-MM-1; sleep 0.2; done
-      preDeviceCommands = ''
-        echo "Creating a heartbeat counter at 0x1bfff0000"
-        sh -c 'hb=0; while [ 1 ]; do let hb=$hb+1; devmem 0x1bfff0000 32 $hb; done' &
-      ''
-      +
+      preDeviceCommands =
       # Run our memtool to hang the kernel here.
       ''
         memtool
       ''
       +
+      ''
+        echo "Creating a heartbeat counter at 0x1bfff0000"
+        sh -c 'hb=0; while [ 1 ]; do let hb=$hb+1; devmem 0x1bfff0000 32 $hb; done' &
+      ''
+      +
       # Disable proactive compaction. May be better to disable CONFIG_COMPACTION.
       ''
         echo 0 > /proc/sys/vm/compaction_proactiveness