diff --git a/loopy/preprocess.py b/loopy/preprocess.py
index 60643f55999d76347674ad7ceccfd7890d7bf1a1..600fe983e94e6b35dbb4d0627040a0c0af0bfcfb 100644
--- a/loopy/preprocess.py
+++ b/loopy/preprocess.py
@@ -289,7 +289,7 @@ def mark_local_temporaries(kernel):
 
             continue
 
-        is_local = wants_to_be_local_per_insn[0]
+        is_local = any(wants_to_be_local_per_insn)
 
         from pytools import all
         if not all(wtbl == is_local for wtbl in wants_to_be_local_per_insn):