diff --git a/include/fmt/compile.h b/include/fmt/compile.h
index 94e13c02..34a581d4 100644
--- a/include/fmt/compile.h
+++ b/include/fmt/compile.h
@@ -448,20 +448,18 @@ constexpr auto compile_format_string(S format_str) {
       } else if constexpr (arg_id_result.arg_id.kind == arg_id_kind::name) {
         constexpr auto arg_index =
             get_arg_index_by_name(arg_id_result.arg_id.val.name, Args{});
-        if constexpr (arg_index != invalid_arg_index) {
+        if constexpr (arg_index >= 0) {
           constexpr auto next_id =
               ID != manual_indexing_id ? ID + 1 : manual_indexing_id;
           return parse_replacement_field_then_tail<
               decltype(get_type<arg_index, Args>::value), Args, arg_id_end_pos,
               arg_index, next_id>(format_str);
-        } else {
-          if constexpr (c == '}') {
-            return parse_tail<Args, arg_id_end_pos + 1, ID>(
-                runtime_named_field<char_type>{arg_id_result.arg_id.val.name},
-                format_str);
-          } else if constexpr (c == ':') {
-            return unknown_format();  // no type info for specs parsing
-          }
+        } else if constexpr (c == '}') {
+          return parse_tail<Args, arg_id_end_pos + 1, ID>(
+              runtime_named_field<char_type>{arg_id_result.arg_id.val.name},
+              format_str);
+        } else if constexpr (c == ':') {
+          return unknown_format();  // no type info for specs parsing
         }
       }
     }
diff --git a/include/fmt/core.h b/include/fmt/core.h
index f4d4aaf4..df45a5b9 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -241,12 +241,6 @@
 #  endif
 #endif
 
-#if defined __cpp_inline_variables && __cpp_inline_variables >= 201606L
-#  define FMT_INLINE_VARIABLE inline
-#else
-#  define FMT_INLINE_VARIABLE
-#endif
-
 // Enable minimal optimizations for more compact code in debug mode.
 FMT_GCC_PRAGMA("GCC push_options")
 #if !defined(__OPTIMIZE__) && !defined(__NVCOMPILER) && !defined(__LCC__) && \
@@ -2543,8 +2537,6 @@ FMT_CONSTEXPR auto check_char_specs(const format_specs<Char>& specs) -> bool {
   return true;
 }
 
-constexpr FMT_INLINE_VARIABLE int invalid_arg_index = -1;
-
 #if FMT_USE_NONTYPE_TEMPLATE_ARGS
 template <int N, typename T, typename... Args, typename Char>
 constexpr auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
@@ -2554,7 +2546,7 @@ constexpr auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
   if constexpr (sizeof...(Args) > 0)
     return get_arg_index_by_name<N + 1, Args...>(name);
   (void)name;  // Workaround an MSVC bug about "unused" parameter.
-  return invalid_arg_index;
+  return -1;
 }
 #endif
 
@@ -2565,7 +2557,7 @@ FMT_CONSTEXPR auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
     return get_arg_index_by_name<0, Args...>(name);
 #endif
   (void)name;
-  return invalid_arg_index;
+  return -1;
 }
 
 template <typename Char, typename... Args> class format_string_checker {
@@ -2598,7 +2590,7 @@ template <typename Char, typename... Args> class format_string_checker {
   FMT_CONSTEXPR auto on_arg_id(basic_string_view<Char> id) -> int {
 #if FMT_USE_NONTYPE_TEMPLATE_ARGS
     auto index = get_arg_index_by_name<Args...>(id);
-    if (index == invalid_arg_index) on_error("named argument is not found");
+    if (index < 0) on_error("named argument is not found");
     return index;
 #else
     (void)id;
diff --git a/include/fmt/format.h b/include/fmt/format.h
index c78364a0..a65d3765 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -53,6 +53,12 @@
 #  define FMT_END_DETAIL_NAMESPACE }
 #endif
 
+#if defined __cpp_inline_variables && __cpp_inline_variables >= 201606L
+#  define FMT_INLINE_VARIABLE inline
+#else
+#  define FMT_INLINE_VARIABLE
+#endif
+
 #if FMT_HAS_CPP17_ATTRIBUTE(fallthrough)
 #  define FMT_FALLTHROUGH [[fallthrough]]
 #elif defined(__clang__)