diff --git a/pkg/noun/jets/c/mas.c b/pkg/noun/jets/c/mas.c
index 4914a35acf..4542647794 100644
--- a/pkg/noun/jets/c/mas.c
+++ b/pkg/noun/jets/c/mas.c
@@ -14,8 +14,8 @@ u3qc_mas(u3_atom a)
     }
     else {
       b_w = c3_bits_word(a);
-      a  &= ~(1 << (b_w - 1));
-      a  |=  (1 << (b_w - 2));
+      a  &= ~((c3_w)1 << (b_w - 1));
+      a  |=  ((c3_w)1 << (b_w - 2));
       return a;
     }
   }
@@ -37,8 +37,8 @@ u3qc_mas(u3_atom a)
       top_w = sab_u.buf_w[len_w];
 
       b_w   &= 31;
-      top_w &= (1 << (b_w - 1)) - 1;
-      top_w |= (1 << (b_w - 2));
+      top_w &= ((c3_w)1 << (b_w - 1)) - 1;
+      top_w |= ((c3_w)1 << (b_w - 2));
 
       sab_u.buf_w[len_w] = top_w;
       return u3i_slab_moot(&sab_u);