diff --git a/arraycontext/container/arithmetic.py b/arraycontext/container/arithmetic.py
index 7e5da8b7d557c4ffb64d616aaf88c477ab352a5c..f3fb4af79a98fa732b1a2f4a784cd2952377cdef 100644
--- a/arraycontext/container/arithmetic.py
+++ b/arraycontext/container/arithmetic.py
@@ -42,12 +42,12 @@ T = TypeVar("T")
 
 
 class _OpClass(enum.Enum):
-    ARITHMETIC = enum.auto
-    MATMUL = enum.auto
-    BITWISE = enum.auto
-    SHIFT = enum.auto
-    EQ_COMPARISON = enum.auto
-    REL_COMPARISON = enum.auto
+    ARITHMETIC = enum.auto()
+    MATMUL = enum.auto()
+    BITWISE = enum.auto()
+    SHIFT = enum.auto()
+    EQ_COMPARISON = enum.auto()
+    REL_COMPARISON = enum.auto()
 
 
 _UNARY_OP_AND_DUNDER = [