diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index de368f2342..218076af0a 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -884,6 +884,7 @@ pub enum ComptimeVarKind {
 	generic_param // generic fn parameter
 	generic_var   // generic var
 	smartcast     // smart cast when used in `is v` (when `v` is from $for .variants)
+	aggregate     // aggregate var
 }
 
 @[minify]
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 26c656d6ec..2b715e9af2 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -4331,6 +4331,8 @@ fn (mut c Checker) smartcast(mut expr ast.Expr, cur_type ast.Type, to_type_ ast.
 				is_inherited = expr.obj.is_inherited
 				ct_type_var = if is_comptime {
 					.smartcast
+				} else if c.table.type_kind(to_type_) == .aggregate {
+					.aggregate
 				} else {
 					.no_comptime
 				}
diff --git a/vlib/v/checker/str.v b/vlib/v/checker/str.v
index 9209ac7d2c..cf12236d85 100644
--- a/vlib/v/checker/str.v
+++ b/vlib/v/checker/str.v
@@ -32,7 +32,7 @@ fn (mut c Checker) get_default_fmt(ftyp ast.Type, typ ast.Type) u8 {
 			return `s`
 		}
 		if ftyp in [ast.string_type, ast.bool_type]
-			|| sym.kind in [.enum, .array, .array_fixed, .struct, .map, .multi_return, .sum_type, .interface, .none]
+			|| sym.kind in [.enum, .array, .array_fixed, .struct, .map, .multi_return, .sum_type, .interface, .aggregate, .none]
 			|| ftyp.has_option_or_result() || sym.has_method('str') {
 			return `s`
 		} else {
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index ab8428d01f..db208129da 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -5022,7 +5022,7 @@ fn (mut g Gen) ident(node ast.Ident) {
 	if node.info is ast.IdentVar {
 		if node.obj is ast.Var {
 			if !g.is_assign_lhs
-				&& node.obj.ct_type_var !in [.smartcast, .generic_param, .no_comptime] {
+				&& node.obj.ct_type_var !in [.smartcast, .generic_param, .no_comptime, .aggregate] {
 				comptime_type := g.type_resolver.get_type(node)
 				if comptime_type.has_flag(.option) {
 					if (g.inside_opt_or_res || g.left_is_opt) && node.or_expr.kind == .absent {
diff --git a/vlib/v/gen/c/infix.v b/vlib/v/gen/c/infix.v
index f3a2227f89..c1fa6a72a7 100644
--- a/vlib/v/gen/c/infix.v
+++ b/vlib/v/gen/c/infix.v
@@ -836,11 +836,7 @@ fn (mut g Gen) infix_expr_in_optimization(left ast.Expr, left_type ast.Type, rig
 fn (mut g Gen) infix_expr_is_op(node ast.InfixExpr) {
 	mut left_sym := g.table.sym(g.unwrap_generic(g.type_resolver.get_type_or_default(node.left,
 		node.left_type)))
-	is_aggregate := left_sym.kind == .aggregate
-	if is_aggregate {
-		parent_left_type := (left_sym.info as ast.Aggregate).sum_type
-		left_sym = g.table.sym(parent_left_type)
-	}
+	is_aggregate := node.left is ast.Ident && g.comptime.get_ct_type_var(node.left) == .aggregate
 	right_sym := g.table.sym(node.right_type)
 	if left_sym.kind == .interface && right_sym.kind == .interface {
 		g.gen_interface_is_op(node)
@@ -880,7 +876,7 @@ fn (mut g Gen) infix_expr_is_op(node ast.InfixExpr) {
 		sub_sym := g.table.sym(sub_type)
 		g.write('_${left_sym.cname}_${sub_sym.cname}_index')
 		return
-	} else if left_sym.kind == .sum_type {
+	} else if left_sym.kind == .sum_type || is_aggregate {
 		g.write('_typ ${cmp_op} ')
 	}
 	if node.right is ast.None {
diff --git a/vlib/v/gen/c/match.v b/vlib/v/gen/c/match.v
index 5795489ba4..772e6271f6 100644
--- a/vlib/v/gen/c/match.v
+++ b/vlib/v/gen/c/match.v
@@ -218,6 +218,9 @@ fn (mut g Gen) match_expr_sumtype(node ast.MatchExpr, is_expr bool, cond_var str
 				}
 				cur_expr := unsafe { &branch.exprs[sumtype_index] }
 				if cond_sym.kind == .sum_type {
+					if cur_expr is ast.TypeNode {
+						g.type_resolver.update_ct_type(cond_var, cur_expr.typ)
+					}
 					g.write('${dot_or_ptr}_typ == ')
 					if cur_expr is ast.None {
 						g.write('${ast.none_type.idx()} /* none */')
diff --git a/vlib/v/tests/comptime/comptime_aggregate_var_test.v b/vlib/v/tests/comptime/comptime_aggregate_var_test.v
new file mode 100644
index 0000000000..6ba35886cb
--- /dev/null
+++ b/vlib/v/tests/comptime/comptime_aggregate_var_test.v
@@ -0,0 +1,25 @@
+module main
+
+type Value = int | i64 | u64 | string | []u8
+
+fn d(val Value) string {
+	match val {
+		int, i64, u64, []u8 {
+			s := sizeof(val)
+			x := val
+			return 'Value is number or byte array, size=${s} ${x}'
+		}
+		string {
+			x := val
+			return 'Value is string: ${x}'
+		}
+	}
+}
+
+fn test_main() {
+	assert d(Value(0)) == 'Value is number or byte array, size=4 0'
+	assert d(Value(i64(1))) == 'Value is number or byte array, size=8 1'
+	assert d(Value(u64(2))) == 'Value is number or byte array, size=8 2'
+	assert d(Value([u8(1), 2])) == 'Value is number or byte array, size=32 [1, 2]'
+	assert d(Value('')) == 'Value is string: '
+}
diff --git a/vlib/v/tests/typeof_aggregate_test.v b/vlib/v/tests/typeof_aggregate_test.v
index 839d874288..8a21f0f645 100644
--- a/vlib/v/tests/typeof_aggregate_test.v
+++ b/vlib/v/tests/typeof_aggregate_test.v
@@ -41,6 +41,6 @@ fn test_typeof_aggregate() {
 
 	assert rets.len == 3
 	assert rets[0] == 'The type of `a` is `Foo`'
-	assert rets[1] == 'The type of `a` is `(Bar | Baz | Bazaar)` and its text says bar'
-	assert rets[2] == 'The type of `a` is `(Bar | Baz | Bazaar)` and its text says baz'
+	assert rets[1] == 'The type of `a` is `Bar` and its text says bar'
+	assert rets[2] == 'The type of `a` is `Baz` and its text says baz'
 }
diff --git a/vlib/v/type_resolver/type_resolver.v b/vlib/v/type_resolver/type_resolver.v
index 4d9cb7df31..01530ee95f 100644
--- a/vlib/v/type_resolver/type_resolver.v
+++ b/vlib/v/type_resolver/type_resolver.v
@@ -190,6 +190,13 @@ pub fn (mut t TypeResolver) get_type(node ast.Expr) ast.Type {
 						ctyp
 					}
 				}
+				.aggregate {
+					t.get_ct_type_or_default(node.name, if node.obj.smartcasts.len > 0 {
+						node.obj.smartcasts.last()
+					} else {
+						node.obj.typ
+					})
+				}
 				.key_var, .value_var {
 					// key and value variables from normal for stmt
 					t.get_ct_type_or_default(node.name, ast.void_type)