diff --git a/libs/iovm/source/IoList.c b/libs/iovm/source/IoList.c
index b62b25809..ed689ad72 100644
--- a/libs/iovm/source/IoList.c
+++ b/libs/iovm/source/IoList.c
@@ -1116,7 +1116,6 @@ IO_METHOD(IoList, fromEncodedList) {
             }
             uint32_t id = *((uint32_t *)(d + index));
             IoMessage_setCachedArg_to_(rm, 0, IONUMBER(id));
-            IoMessage_setCachedArg_to_(rm, 0, IONIL(self));
 
             index += sizeof(uint32_t);
 
@@ -1124,6 +1123,7 @@ IO_METHOD(IoList, fromEncodedList) {
                 IoObject *result = IoObject_perform(locals, locals, rm);
                 List_append_(list, result);
             }
+            IoMessage_setCachedArg_to_(rm, 0, IONIL(self));
         } else {
             IOASSERT(0, "unrecognized encoded type");
         }
diff --git a/libs/iovm/tests/correctness/ListTest.io b/libs/iovm/tests/correctness/ListTest.io
index 0cb330efe..d3843dbb4 100644
--- a/libs/iovm/tests/correctness/ListTest.io
+++ b/libs/iovm/tests/correctness/ListTest.io
@@ -492,6 +492,41 @@ ListTest := UnitTest clone do(
 		assertEquals(t, t asEncodedList asDecodedList)
 	)
 
+	# Regression for IoList.c REFERENCE decode: objectForReferenceId must receive
+	# IONUMBER(id) (clear cached arg only after perform). Same id=42 as bug.io.
+	# Uses manual bytes (IOLIST_ENCODING_TYPE_REFERENCE + uint32 LE) so this test
+	# does not depend on asEncodedList or Lobby referenceIdForObject under doString.
+	testEncodedListFromEncodedListReferenceId := method(
+		ref := Object clone
+		hadObj := Lobby hasLocalSlot("objectForReferenceId")
+		hadStash := Lobby hasLocalSlot("referenceRoundTripRef")
+		prevObj := if(hadObj, Lobby getSlot("objectForReferenceId"), nil)
+		prevStash := if(hadStash, Lobby getSlot("referenceRoundTripRef"), nil)
+
+		Lobby referenceRoundTripRef := ref
+		Lobby do(
+			objectForReferenceId := method(id,
+				if(id isIdenticalTo(42), Lobby getSlot("referenceRoundTripRef"), nil)
+			)
+		)
+
+		enc := ("" asMutable)
+		enc appendSeq(3 asCharacter, 0 asCharacter, 0 asCharacter)
+		enc appendSeq(42 asCharacter, 0 asCharacter, 0 asCharacter, 0 asCharacter)
+		dec := List fromEncodedList(enc)
+		assertEquals(1, dec size)
+		assertTrue(dec first isIdenticalTo(ref))
+
+		if(hadObj,
+			Lobby do(objectForReferenceId := prevObj),
+			Lobby removeSlot("objectForReferenceId")
+		)
+		if(hadStash,
+			Lobby do(referenceRoundTripRef := prevStash),
+			Lobby removeSlot("referenceRoundTripRef")
+		)
+	)
+
     testSlice := method(
         a := list(1, 2, 3, 4, 5, 6)
         assertEquals(a, a slice(0))