diff --git a/LANGUAGE.md b/LANGUAGE.md
index 8201b30..f7798d9 100644
--- a/LANGUAGE.md
+++ b/LANGUAGE.md
@@ -44,7 +44,7 @@ roadmap and milestone history.
 - compiler-reordered native structs with fields laid out by decreasing alignment (declaration order breaks ties and remains the reflection/diagnostic order), opaque nominal records with `Name :: opaque`, complete source-order `c_struct { ... }`, keyed record literals, native untagged unions, and native tagged unions `union(Enum)` / `union(enum)`
 - named native struct fields may declare defaults with `field T = expression`; keyed literals use defaults for omitted fields and explicit initializers override them
 - void-payload tagged-union variants, anonymous struct payloads, contextual `.variant`, `.variant{payload}`, and `.variant{field = value}` construction
-- native sum composition with `A | B` for unbacked enums and tagged unions, optionally grouped as `(A | B)`, using program-global `u16` variant ids
+- native sum composition with `A | B` for unbacked enums and tagged unions, optionally grouped as `(A | B)`, using program-global `u16` variant ids; parenthesized types allow newlines after `(`, before `)`, and on either side of `|`, including in aliases and fallible signatures
 - fallible channel types `T ! E`, where `E` is a native enum, native struct, tagged union, or supported sum composition; `void ! E` functions complete successfully on fallthrough, and void-success `catch` handlers may fall through without `yield`
 - bodyful local functions and root `main` may write `T!` to infer a specialization-local error channel from propagated `try` expressions and concretely typed error returns; inference composes only existing named error types, never synthesizes variants, and requires at least one inferred error
 
diff --git a/compiler/parser/parser.odin b/compiler/parser/parser.odin
index d9279e7..89de3c2 100644
--- a/compiler/parser/parser.odin
+++ b/compiler/parser/parser.odin
@@ -429,7 +429,8 @@ parse_type_atom :: proc(parser: ^Parser) -> ast.Type_Syntax {
 		return types.BOOL
 	case .Left_Paren:
 		advance(parser)
-		grouped := parse_type(parser)
+		skip_newlines(parser)
+		grouped := parse_type_pipe_tail(parser, parse_type_atom(parser), true)
 		if _, ok := allow(parser, .Right_Paren); !ok {
 			source.add(parser.diagnostics, current(parser).span, "expected ')' after grouped type")
 		}
@@ -533,10 +534,19 @@ sum_syntax_requires_resolution :: proc(parser: ^Parser, value: types.Type, depth
 	return false
 }
 
-parse_type_pipe_tail :: proc(parser: ^Parser, left: ast.Type_Syntax) -> ast.Type_Syntax {
+parse_type_pipe_tail :: proc(parser: ^Parser, left: ast.Type_Syntax, multiline := false) -> ast.Type_Syntax {
 	result := left
-	for current(parser).kind == .Pipe {
+	for {
+		if multiline {
+			skip_newlines(parser)
+		}
+		if current(parser).kind != .Pipe {
+			break
+		}
 		operator := advance(parser)
+		if multiline {
+			skip_newlines(parser)
+		}
 		right := parse_type_atom(parser)
 		composed, compose_error := types.compose_sum(&parser.module.type_store, result, right)
 		if compose_error == .Unsupported {
diff --git a/compiler_tests.odin b/compiler_tests.odin
index a233489..a74cbd3 100644
--- a/compiler_tests.odin
+++ b/compiler_tests.odin
@@ -7680,6 +7680,65 @@ main func() i32 {
 	testing.expect(t, strings.contains(llvm_text, "call void @llvm.memcpy.p0.p0.i64"))
 }
 
+@(test)
+multiline_grouped_sum_types_compile_and_run :: proc(t: ^testing.T) {
+	directory :: "/tmp/brolang-test-multiline-sums"
+	output := "/tmp/brolang-test-multiline-sums-output"
+	_ = os2.remove_all(directory)
+	defer _ = os2.remove_all(directory)
+	defer _ = os.remove(output)
+	testing.expect(t, os.make_directory(directory) == nil)
+	testing.expect(t, os.make_directory(directory + "/errors") == nil)
+	errors_text := `AllocError :: enum { alloc }
+CapacityError :: enum { capacity }
+SourceError :: union(enum) { source i32 }
+`
+	testing.expect(t, os.write_entire_file(directory + "/errors/errors.hon", transmute([]byte)errors_text))
+	text := `errors :: import "errors"
+@hide:file
+DriverError :: alias (
+	errors.AllocError
+	| (
+		errors.CapacityError |
+		errors.SourceError
+	)
+)
+code func(err DriverError) i32 {
+	return match err {
+		.alloc: 1
+		.capacity: 2
+		.source |value|: value
+	}
+}
+fail func() void ! (
+	errors.AllocError
+	|
+	errors.CapacityError
+) {
+	return .capacity
+}
+main func() i32 {
+	if (code(.alloc) != 1) return 1
+	if (code(.capacity) != 2) return 2
+	if (code(.source{42}) != 42) return 3
+	result := 0
+	fail() catch |err| {
+		result = code(err)
+	}
+	if (result != 2) return 4
+	return 0
+}
+`
+	testing.expect(t, os.write_entire_file(directory + "/main.hon", transmute([]byte)text))
+	status := compiler_core.compile_package(directory, output)
+	testing.expect_value(t, status, 0)
+	if status != 0 {
+		return
+	}
+	state := run_executable(output)
+	testing.expect_value(t, state.exit_code, 0)
+}
+
 @(test)
 anonymous_struct_payloads_and_keyed_payload_sugar_compile :: proc(t: ^testing.T) {
 	text := `PayloadError :: union(enum) {