diff --git a/src/dev/sparc/mm_disk.cc b/src/dev/sparc/mm_disk.cc
index b8cabd0cf6..81c5c589ac 100644
--- a/src/dev/sparc/mm_disk.cc
+++ b/src/dev/sparc/mm_disk.cc
@@ -45,7 +45,7 @@
 #include "sim/system.hh"
 
 MmDisk::MmDisk(Params *p)
-    : BasicPioDevice(p), image(p->image), curSector((uint64_t)-1), dirty(false)
+    : BasicPioDevice(p), image(p->image), curSector((off_t)-1), dirty(false)
 {
     std::memset(&diskData, 0, SectorSize);
     pioSize = image->size() * SectorSize;