diff --git a/src/daglib/set.py b/src/daglib/set.py
index 3c13180..a306a1c 100644
--- a/src/daglib/set.py
+++ b/src/daglib/set.py
@@ -57,6 +57,17 @@ class DAGSet(MutableSet[T]):
 
     # --- in-place operator support ---
 
+    def __ior__(self, other: Iterable[T]) -> DAGSet[T]:
+        # a |= b => union update
+        match other:
+            case str():
+                other = {other}
+            case Iterable():
+                other = set(other)
+            case _:
+                other = {other}
+        return super().__ior__(other)
+
     def __iadd__(self, other: Iterable[T]) -> DAGSet[T]:
         # a += b => update/extend
         match other: