diff --git a/subspace/choice/choice.h b/subspace/choice/choice.h
index 7b168cc12..d0a340432 100644
--- a/subspace/choice/choice.h
+++ b/subspace/choice/choice.h
@@ -650,7 +650,7 @@ struct fmt::formatter<
                                  Tags...>;
 
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return ctx.begin();
   }
 
diff --git a/subspace/choice/choice_unittest.cc b/subspace/choice/choice_unittest.cc
index c6e63308a..61c072b7a 100644
--- a/subspace/choice/choice_unittest.cc
+++ b/subspace/choice/choice_unittest.cc
@@ -34,7 +34,7 @@ enum class Order {
 template <class Char>
 struct fmt::formatter<Order, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return ctx.begin();
   }
 
diff --git a/subspace/containers/array.h b/subspace/containers/array.h
index 4fc41be82..3be02a98e 100644
--- a/subspace/containers/array.h
+++ b/subspace/containers/array.h
@@ -468,7 +468,7 @@ struct tuple_element<I, ::sus::containers::Array<T, N>> {
 template <class T, size_t N, class Char>
 struct fmt::formatter<::sus::containers::Array<T, N>, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return underlying_.parse(ctx);
   }
 
diff --git a/subspace/containers/slice.h b/subspace/containers/slice.h
index 77c80b381..70a6cb1e5 100644
--- a/subspace/containers/slice.h
+++ b/subspace/containers/slice.h
@@ -308,7 +308,7 @@ using ::sus::iter::__private::end;
 template <class T, class Char>
 struct fmt::formatter<::sus::containers::Slice<T>, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return underlying_.parse(ctx);
   }
 
@@ -336,7 +336,7 @@ sus__format_to_stream(sus::containers, Slice, T);
 template <class T, class Char>
 struct fmt::formatter<::sus::containers::SliceMut<T>, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return underlying_.parse(ctx);
   }
 
diff --git a/subspace/containers/vec.h b/subspace/containers/vec.h
index 4af46ff8c..61cbfc99b 100644
--- a/subspace/containers/vec.h
+++ b/subspace/containers/vec.h
@@ -702,7 +702,7 @@ template <class... Ts>
 template <class T, class Char>
 struct fmt::formatter<::sus::containers::Vec<T>, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return underlying_.parse(ctx);
   }
 
diff --git a/subspace/marker/unsafe.h b/subspace/marker/unsafe.h
index 9e7a95536..31d16722c 100644
--- a/subspace/marker/unsafe.h
+++ b/subspace/marker/unsafe.h
@@ -52,7 +52,7 @@ constexpr inline auto unsafe_fn = UnsafeFnMarker();
 template <class Char>
 struct fmt::formatter<::sus::marker::UnsafeFnMarker, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return ctx.begin();
   }
 
diff --git a/subspace/mem/nonnull.h b/subspace/mem/nonnull.h
index ac26a08c2..d8c15fa05 100644
--- a/subspace/mem/nonnull.h
+++ b/subspace/mem/nonnull.h
@@ -216,7 +216,7 @@ constexpr inline __private::NonNullMarker<T> nonnull(T& t) {
 template <class T, class Char>
 struct fmt::formatter<::sus::mem::NonNull<T>, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return underlying_.parse(ctx);
   }
 
diff --git a/subspace/num/__private/float_methods_impl.inc b/subspace/num/__private/float_methods_impl.inc
index 5fd5a74be..7fcf2679d 100644
--- a/subspace/num/__private/float_methods_impl.inc
+++ b/subspace/num/__private/float_methods_impl.inc
@@ -79,7 +79,7 @@ struct std::equal_to<::sus::num::_self> {
 template <class Char>
 struct fmt::formatter<::sus::num::_self, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return underlying_.parse(ctx);
   }
 
diff --git a/subspace/num/__private/signed_integer_methods_impl.inc b/subspace/num/__private/signed_integer_methods_impl.inc
index 719f59703..b2473751a 100644
--- a/subspace/num/__private/signed_integer_methods_impl.inc
+++ b/subspace/num/__private/signed_integer_methods_impl.inc
@@ -119,7 +119,7 @@ struct std::equal_to<::sus::num::_self> {
 template <class Char>
 struct fmt::formatter<::sus::num::_self, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return underlying_.parse(ctx);
   }
 
diff --git a/subspace/num/__private/unsigned_integer_methods_impl.inc b/subspace/num/__private/unsigned_integer_methods_impl.inc
index 6bfd0e9ff..0316ee417 100644
--- a/subspace/num/__private/unsigned_integer_methods_impl.inc
+++ b/subspace/num/__private/unsigned_integer_methods_impl.inc
@@ -390,7 +390,7 @@ struct std::equal_to<::sus::num::_self> {
 template <class Char>
 struct fmt::formatter<::sus::num::_self, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return underlying_.parse(ctx);
   }
 
diff --git a/subspace/ops/range.h b/subspace/ops/range.h
index b021d6e4d..f1eb9fe1b 100644
--- a/subspace/ops/range.h
+++ b/subspace/ops/range.h
@@ -416,7 +416,7 @@ class [[sus_trivial_abi]] RangeFull final {
 template <class T, class Char>
 struct fmt::formatter<::sus::ops::Range<T>, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return underlying_.parse(ctx);
   }
 
@@ -442,7 +442,7 @@ sus__format_to_stream(sus::ops, Range, T);
 template <class T, class Char>
 struct fmt::formatter<::sus::ops::RangeFrom<T>, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return underlying_.parse(ctx);
   }
 
@@ -467,7 +467,7 @@ sus__format_to_stream(sus::ops, RangeFrom, T);
 template <class T, class Char>
 struct fmt::formatter<::sus::ops::RangeTo<T>, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return underlying_.parse(ctx);
   }
 
@@ -492,7 +492,7 @@ sus__format_to_stream(sus::ops, RangeTo, T);
 template <class T, class Char>
 struct fmt::formatter<::sus::ops::RangeFull<T>, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return underlying_.parse(ctx);
   }
 
diff --git a/subspace/option/option.h b/subspace/option/option.h
index 698c1cf08..22bc61da6 100644
--- a/subspace/option/option.h
+++ b/subspace/option/option.h
@@ -1101,7 +1101,7 @@ struct std::equal_to<::sus::option::Option<T>> {
 template <class T, class Char>
 struct fmt::formatter<::sus::option::Option<T>, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return underlying_.parse(ctx);
   }
 
diff --git a/subspace/result/result.h b/subspace/result/result.h
index 228b1d1d6..7d84254af 100644
--- a/subspace/result/result.h
+++ b/subspace/result/result.h
@@ -788,7 +788,7 @@ struct std::equal_to<::sus::result::Result<T, E>> {
 template <class T, class E, class Char>
 struct fmt::formatter<::sus::result::Result<T, E>, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return underlying_ok_.parse(ctx);
   }
 
diff --git a/subspace/string/__private/any_formatter.h b/subspace/string/__private/any_formatter.h
index 329d6339c..dc364905b 100644
--- a/subspace/string/__private/any_formatter.h
+++ b/subspace/string/__private/any_formatter.h
@@ -48,7 +48,7 @@ auto format_void(auto out) {
 template <class Char>
 struct VoidFormatter {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return ctx.begin();
   }
   template <class T, class FormatContext>
diff --git a/subspace/string/__private/bytes_formatter.h b/subspace/string/__private/bytes_formatter.h
index 6ffc85069..bb3fd8c33 100644
--- a/subspace/string/__private/bytes_formatter.h
+++ b/subspace/string/__private/bytes_formatter.h
@@ -45,7 +45,7 @@ auto format_bytes(auto out, fmt::string_view bytes) {
 template <class Char>
 struct BytesFormatter {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return ctx.begin();
   }
 
diff --git a/subspace/tuple/tuple.h b/subspace/tuple/tuple.h
index 3757b1723..76802bfe0 100644
--- a/subspace/tuple/tuple.h
+++ b/subspace/tuple/tuple.h
@@ -298,7 +298,7 @@ struct tuple_element<0, ::sus::tuple_type::Tuple<T, Types...>> {
 template <class... Types, class Char>
 struct fmt::formatter<::sus::tuple_type::Tuple<Types...>, Char> {
   template <class ParseContext>
-  constexpr decltype(auto) parse(ParseContext& ctx) {
+  constexpr auto parse(ParseContext& ctx) {
     return ctx.begin();
   }