diff --git a/tests/qemu-iotests/051 b/tests/qemu-iotests/051
index ce942a5444..53bcdbc911 100755
--- a/tests/qemu-iotests/051
+++ b/tests/qemu-iotests/051
@@ -377,6 +377,10 @@ printf %b "qemu-io $device_id \"write -P 0x33 0 4k\"\ncommit $device_id\n" |
 $QEMU_IO -c "read -P 0x33 0 4k" "$TEST_IMG" | _filter_qemu_io
 
 # Using snapshot=on with a non-existent TMPDIR
+if [ "${VALGRIND_QEMU_VM}" == "y" ]; then
+    _casenotrun "Valgrind needs a valid TMPDIR for itself"
+fi
+VALGRIND_QEMU_VM= \
 TMPDIR=/nonexistent run_qemu -drive driver=null-co,snapshot=on
 
 # Using snapshot=on together with read-only=on