diff --git a/src/arch/alpha/linux/threadinfo.hh b/src/arch/alpha/linux/threadinfo.hh
index caeb69f15e..b9ffe02ae9 100644
--- a/src/arch/alpha/linux/threadinfo.hh
+++ b/src/arch/alpha/linux/threadinfo.hh
@@ -57,7 +57,7 @@ class ThreadInfo
          * thread_info struct. So we can get the address by masking off
          * the lower 14 bits.
          */
-        current = tc->readIntReg(TheISA::StackPointerReg) & ~0x3fff;
+        current = tc->readIntReg(TheISA::StackPointerReg) & ~ULL(0x3fff);
         return VPtr<thread_info>(tc, current);
     }