diff --git a/opal/mca/paffinity/linux/paffinity_linux_module.c b/opal/mca/paffinity/linux/paffinity_linux_module.c
index 2418ec0a95..edb65a8b34 100644
--- a/opal/mca/paffinity/linux/paffinity_linux_module.c
+++ b/opal/mca/paffinity/linux/paffinity_linux_module.c
@@ -149,7 +149,7 @@ static int linux_module_set(int id)
     }
     byte = id / 8;
     bit = id % 8;
-    mask[byte] = 1 << bit;
+    ((char *) mask)[byte] = 1 << bit;
 
     ret = sched_setaffinity(0, len, mask);