diff --git a/lib/memory.c b/lib/memory.c
index eb67072..9ed5e10 100644
--- a/lib/memory.c
+++ b/lib/memory.c
@@ -501,7 +501,7 @@
        * Just hacked to make it not warn on 'smaller' machines. 
        * Static compiler analysis should mean no extra code
        */
-      if (bytes & (1 << (sizeof (unsigned long) >= 8 ? 39 : 0)))
+      if (bytes & (1UL << (sizeof (unsigned long) >= 8 ? 39 : 0)))
         t++;
       snprintf (buf, len, "%4d TiB", t);
     }