diff --git a/loopy/kernel/instruction.py b/loopy/kernel/instruction.py
index b409f446b8b2b057b26e37df2120a62967397f92..3536537103796bb3408af6c5426ecffbf34a3267 100644
--- a/loopy/kernel/instruction.py
+++ b/loopy/kernel/instruction.py
@@ -210,6 +210,9 @@ class InstructionBase(Record):
         if tags is None:
             tags = frozenset()
 
+        if priority is None:
+            priority = 0
+
         if not isinstance(tags, frozenset):
             # was previously allowed to be tuple
             tags = frozenset(tags)