diff --git a/linera-witty/tests/common/types.rs b/linera-witty/tests/common/types.rs
index 8b2bc439250..006f1c2f679 100644
--- a/linera-witty/tests/common/types.rs
+++ b/linera-witty/tests/common/types.rs
@@ -3,7 +3,7 @@
 
 //! Dummy types used in tests.
 
-use std::rc::Rc;
+use std::{rc::Rc, sync::Arc};
 
 use linera_witty::{WitLoad, WitStore, WitType};
 
@@ -76,4 +76,5 @@ pub enum SpecializedGenericEnum<A, B> {
 pub struct StructWithHeapFields {
     pub boxed: Box<SimpleWrapper>,
     pub rced: Rc<Leaf>,
+    pub arced: Arc<Enum>,
 }
diff --git a/linera-witty/tests/wit_load.rs b/linera-witty/tests/wit_load.rs
index 2c2d0e0ee30..8580072b83a 100644
--- a/linera-witty/tests/wit_load.rs
+++ b/linera-witty/tests/wit_load.rs
@@ -317,12 +317,16 @@ fn test_heap_allocated_fields() {
             first: false,
             second: 0x201f_1e1d_1c1b_1a19_1817_1615_1413_1211_u128,
         }),
+        arced: Arc::new(Enum::SmallerVariantWithStrictAlignment {
+            inner: 0x2f2e_2d2c_2b2a_2928,
+        }),
     };
 
     test_load_from_memory(
         &[
             1, 2, 3, 4, 5, 6, 7, 8, 0, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
-            25, 26, 27, 28, 29, 30, 31, 32,
+            25, 26, 27, 28, 29, 30, 31, 32, 2, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45,
+            46, 47, 48,
         ],
         expected.clone(),
     );
@@ -332,6 +336,17 @@ fn test_heap_allocated_fields() {
             0_i32,
             0x1817_1615_1413_1211_i64,
             0x201f_1e1d_1c1b_1a19_i64,
+            2_i32,
+            0x2f2e_2d2c_2b2a_2928_i64,
+            0_i32,
+            0_i32,
+            0_i32,
+            0_i32,
+            0_i32,
+            0_i32,
+            0_i32,
+            0_i32,
+            0_i32,
         ],
         expected,
         &[],
diff --git a/linera-witty/tests/wit_store.rs b/linera-witty/tests/wit_store.rs
index 8b7be054a87..68ff2693b95 100644
--- a/linera-witty/tests/wit_store.rs
+++ b/linera-witty/tests/wit_store.rs
@@ -363,13 +363,17 @@ fn test_heap_allocated_fields() {
             first: true,
             second: 0x7071_7273_7475_7677_7879_7a7b_7c7d_7e7f_u128,
         }),
+        arced: Arc::new(Enum::SmallerVariantWithStrictAlignment {
+            inner: 0x4041_4243_4445_4647_u64,
+        }),
     };
 
     test_store_in_memory(
         data.clone(),
         &[
             0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0x7f, 0x7e, 0x7d, 0x7c, 0x7b, 0x7a,
-            0x79, 0x78, 0x77, 0x76, 0x75, 0x74, 0x73, 0x72, 0x71, 0x70,
+            0x79, 0x78, 0x77, 0x76, 0x75, 0x74, 0x73, 0x72, 0x71, 0x70, 2, 0, 0, 0, 0, 0, 0, 0,
+            0x47, 0x46, 0x45, 0x44, 0x43, 0x42, 0x41, 0x40, 0, 0, 0, 0, 0, 0, 0, 0,
         ],
         &[],
     );
@@ -380,6 +384,17 @@ fn test_heap_allocated_fields() {
             1_i32,
             0x7879_7a7b_7c7d_7e7f_i64,
             0x7071_7273_7475_7677_i64,
+            2_i32,
+            0x4041_4243_4445_4647_i64,
+            0,
+            0,
+            0,
+            0,
+            0,
+            0,
+            0,
+            0,
+            0,
         ],
         &[],
     );
diff --git a/linera-witty/tests/wit_type.rs b/linera-witty/tests/wit_type.rs
index 9d672df6cab..4f9094c25d3 100644
--- a/linera-witty/tests/wit_type.rs
+++ b/linera-witty/tests/wit_type.rs
@@ -181,10 +181,17 @@ fn test_specialized_generic_enum_type() {
 #[test]
 fn test_heap_allocated_fields() {
     test_wit_type_implementation::<StructWithHeapFields>(ExpectedMetadata {
-        size: 32,
+        size: 56,
         alignment: 8,
-        flat_layout_length: 4,
+        flat_layout_length: 15,
         declaration: concat!(
+            "    variant enum {\n",
+            "        empty,\n",
+            "        large-variant-with-loose-alignment(\
+                        tuple<s8, s8, s8, s8, s8, s8, s8, s8, s8, s8>\
+                     ),\n",
+            "        smaller-variant-with-strict-alignment(u64),\n",
+            "    }\n\n",
             "    record leaf {\n",
             "        first: bool,\n",
             "        second: u128,\n",
@@ -195,6 +202,7 @@ fn test_heap_allocated_fields() {
             "    record struct-with-heap-fields {\n",
             "        boxed: simple-wrapper,\n",
             "        rced: leaf,\n",
+            "        arced: enum,\n",
             "    }\n\n",
             "    type u128 = tuple<u64, u64>;\n",
         ),