diff --git a/tests/long/10.mcf/test.py b/tests/long/10.mcf/test.py
index cb8acff22d..c4ffb248ad 100644
--- a/tests/long/10.mcf/test.py
+++ b/tests/long/10.mcf/test.py
@@ -31,3 +31,4 @@ from cpu2000 import mcf
 
 workload = mcf(isa, opsys, 'smred')
 root.system.cpu.workload = workload.makeLiveProcess()
+root.system.physmem.range=AddrRange('256MB')