diff --git a/tests/data/specs/aggregate_in_relation.rflx b/tests/data/specs/aggregate_in_relation.rflx
index 547c3eb4f..a1f9bcf50 100644
--- a/tests/data/specs/aggregate_in_relation.rflx
+++ b/tests/data/specs/aggregate_in_relation.rflx
@@ -26,7 +26,10 @@ package Aggregate_In_Relation is
                if Fld_C = [16#CC#, 16#CC#]
             then null
                if Fld_C /= [16#CC#, 16#CC#];
-         Fld_D : D;
+         Fld_D : Opaque
+            with Size => 16
+            then null
+               if Fld_D = Fld_A;
       end message;
 
 end Aggregate_In_Relation;
diff --git a/tests/unit/expression_test.py b/tests/unit/expression_test.py
index 79cb54f21..d6449dee4 100644
--- a/tests/unit/expression_test.py
+++ b/tests/unit/expression_test.py
@@ -1083,7 +1083,8 @@ def test_relation_simplified() -> None:
     )
     assert_equal(Equal(String("Foo Bar"), String("Foo Bar")).simplified(), TRUE)
     assert_equal(
-        Equal(String("Foo"), Aggregate(Number(70), Number(111), Number(111))).simplified(), TRUE
+        Equal(String("Foo"), Aggregate(Number(70), Number(111), Number(111))).simplified(),
+        TRUE,
     )
     assert_equal(
         Equal(
@@ -1097,10 +1098,22 @@ def test_relation_simplified() -> None:
         ).simplified(),
         FALSE,
     )
-    assert_equal(Equal(Number(0), Aggregate(Number(0), Number(1), Number(2))).simplified(), FALSE)
-    assert_equal(Equal(Aggregate(Number(0), Number(1), Number(2)), Number(0)).simplified(), FALSE)
-    assert_equal(NotEqual(Number(4), Aggregate(Number(0), Number(1), Number(2))).simplified(), TRUE)
-    assert_equal(NotEqual(Number(0), Aggregate(Number(0), Number(1), Number(2))).simplified(), TRUE)
+    assert_equal(
+        Equal(Number(0), Aggregate(Number(0), Number(1), Number(2))).simplified(),
+        FALSE,
+    )
+    assert_equal(
+        Equal(Aggregate(Number(0), Number(1), Number(2)), Number(0)).simplified(),
+        FALSE,
+    )
+    assert_equal(
+        NotEqual(Number(4), Aggregate(Number(0), Number(1), Number(2))).simplified(),
+        TRUE,
+    )
+    assert_equal(
+        NotEqual(Number(0), Aggregate(Number(0), Number(1), Number(2))).simplified(),
+        TRUE,
+    )
     assert Equal(TRUE, TRUE).simplified() == TRUE
     assert Equal(TRUE, FALSE).simplified() == FALSE
     assert NotEqual(TRUE, TRUE).simplified() == FALSE
diff --git a/tests/unit/pyrflx_test.py b/tests/unit/pyrflx_test.py
index 1001e018b..ab31f4f5f 100644
--- a/tests/unit/pyrflx_test.py
+++ b/tests/unit/pyrflx_test.py
@@ -1520,6 +1520,6 @@ def test_low_order(low_order_package: Package) -> None:
 
 def test_aggregate_in_relation_valid(aggregate_in_relation_package: Package) -> None:
     msg = aggregate_in_relation_package.new_message("Aggregate_In_Relation_Msg")
-    msg.parse(b"\xAA\xAA\xBB\xCC\xCC\xDD")
-    assert msg.bytestring == b"\xAA\xAA\xBB\xCC\xCC\xDD"
+    msg.parse(b"\xAA\xAA\xBB\xCC\xCC\xAA\xAA")
+    assert msg.bytestring == b"\xAA\xAA\xBB\xCC\xCC\xAA\xAA"
     assert msg.valid_message