diff --git a/code/code_gen/post.py b/code/code_gen/post.py
index 0431106..6c217f3 100644
--- a/code/code_gen/post.py
+++ b/code/code_gen/post.py
@@ -639,7 +639,10 @@ class Stage4():
 
         mask = self.liveness(l, dg)
 
-        narr = mask.astype(np.int).sum(axis=0).max()
+        try:
+            narr = mask.astype(np.int).sum(axis=0).max()
+        except ValueError:
+            narr = 0
 
         array_pool = set([self.array_name.format(i) for i in range(narr)])