diff -r bb10807da889 -r a714221c3c44 src/sim/system.cc
--- a/src/sim/system.cc	Tue Jan 31 22:40:08 2012 -0800
+++ b/src/sim/system.cc	Thu Feb 02 19:02:54 2012 -0800
@@ -296,7 +296,7 @@
 {
     Addr return_addr = pagePtr << LogVMPageSize;
     pagePtr += npages;
-    if (return_addr >= physmem->size())
+    if (return_addr + npages - 1 >= physmem->size())
         fatal("Out of memory, please increase size of physical memory.");
     return return_addr;
 }