diff --git a/src/mem/cache/prefetch/base.cc b/src/mem/cache/prefetch/base.cc
index 3f5b67e6aa..53260ae0d2 100644
--- a/src/mem/cache/prefetch/base.cc
+++ b/src/mem/cache/prefetch/base.cc
@@ -140,7 +140,7 @@ BasePrefetcher::samePage(Addr a, Addr b) const
 Addr
 BasePrefetcher::blockAddress(Addr a) const
 {
-    return a & ~(blkSize-1);
+    return a & ~((Addr)blkSize-1);
 }
 
 Addr