diff --git a/loopy/kernel/instruction.py b/loopy/kernel/instruction.py
index 9b5c7a5b421c8e37e4ddac88b7bf98fa59e32d6e..8213c9584b54917050c586e1b83b6d66d0473798 100644
--- a/loopy/kernel/instruction.py
+++ b/loopy/kernel/instruction.py
@@ -1216,8 +1216,6 @@ class CInstruction(InstructionBase):
             set("iname_exprs code read_variables assignees".split())
     pymbolic_fields = InstructionBase.pymbolic_fields | \
             set("assignees".split())
-    pymbolic_set_fields = InstructionBase.pymbolic_set_fields | \
-            set(["read_variables"])
 
     def __init__(self,
             iname_exprs, code,