diff --git a/sway-core/src/semantic_analysis/ast_node/expression/typed_expression/enum_instantiation.rs b/sway-core/src/semantic_analysis/ast_node/expression/typed_expression/enum_instantiation.rs
index 608d62884f6..d9374d17bb1 100644
--- a/sway-core/src/semantic_analysis/ast_node/expression/typed_expression/enum_instantiation.rs
+++ b/sway-core/src/semantic_analysis/ast_node/expression/typed_expression/enum_instantiation.rs
@@ -90,7 +90,8 @@ pub(crate) fn instantiate_enum(
                 .with_help_text("Enum instantiator must match its declared variant type.")
                 .with_type_annotation(start_type);
 
-            let typed_expr = ty::TyExpression::type_check(handler, enum_ctx, single_expr.clone())?;
+            let mut typed_expr =
+                ty::TyExpression::type_check(handler, enum_ctx, single_expr.clone())?;
 
             // unify the value of the argument with the variant
             handler.scope(|handler| {
@@ -106,6 +107,9 @@ pub(crate) fn instantiate_enum(
                 Ok(())
             })?;
 
+            // Reuse the TypeId so further unification in typed_expr.return_type also affect enum_variant.type_argument.type_id
+            typed_expr.return_type = enum_variant.type_argument.type_id;
+
             // we now know that the instantiator type matches the declared type, via the above tpe
             // check
 
diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/Forc.lock b/test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/Forc.lock
new file mode 100644
index 00000000000..6742225f200
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/Forc.lock
@@ -0,0 +1,16 @@
+[[package]]
+name = "core"
+source = "path+from-root-F6BA7257B3F9949F"
+
+[[package]]
+name = "enum_variant_unification"
+source = "member"
+dependencies = [
+    "core",
+    "std",
+]
+
+[[package]]
+name = "std"
+source = "path+from-root-F6BA7257B3F9949F"
+dependencies = ["core"]
diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/Forc.toml b/test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/Forc.toml
new file mode 100644
index 00000000000..de56d4525f5
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/Forc.toml
@@ -0,0 +1,9 @@
+[project]
+authors = ["Fuel Labs <contact@fuel.sh>"]
+entry = "main.sw"
+license = "Apache-2.0"
+name = "enum_variant_unification"
+
+[dependencies]
+core = { path = "../../../../../../../sway-lib-core" }
+std = { path = "../../../../../../../sway-lib-std" }
diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/src/main.sw b/test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/src/main.sw
new file mode 100644
index 00000000000..4b3b689d709
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/src/main.sw
@@ -0,0 +1,33 @@
+script;
+
+struct S<T> {
+    x: T,
+}
+
+fn main() -> u64 {
+  // https://github.com/FuelLabs/sway/issues/5492
+  let _ = foo();
+  let _ = bar(true);
+
+  // https://github.com/FuelLabs/sway/issues/5581
+  let _: S<Option<u8>>  = S { x: Option::Some(1) };
+
+  0
+}
+
+#[inline(never)]
+fn foo() -> Option<u8> {
+  match Some(true) {
+    Option::Some(_b) => Option::Some(17),
+    Option::None => Option::None,
+  }
+}
+
+#[inline(never)]
+fn bar(b: bool) -> Option<u8> {
+   if(b) {
+     Option::Some(19)
+   } else {
+     Option::None
+   }
+}
\ No newline at end of file
diff --git a/test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/test.toml b/test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/test.toml
new file mode 100644
index 00000000000..8bce66414f9
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_pass/language/enum_variant_unification/test.toml
@@ -0,0 +1,4 @@
+category = "run"
+expected_result = { action = "return", value = 0 }
+validate_abi = false
+expected_warnings = 3