diff --git a/include/fmt/base.h b/include/fmt/base.h
index ab2fcf6f..fc65a36c 100644
--- a/include/fmt/base.h
+++ b/include/fmt/base.h
@@ -161,6 +161,20 @@
 #  define FMT_CATCH(x) if (false)
 #endif
 
+#ifdef FMT_NO_UNIQUE_ADDRESS
+// Use the provided definition.
+#elif FMT_CPLUSPLUS < 202002L
+// Not supported.
+#elif FMT_HAS_CPP_ATTRIBUTE(no_unique_address)
+#  define FMT_NO_UNIQUE_ADDRESS [[no_unique_address]]
+// VS2019 v16.10 and later except clang-cl (https://reviews.llvm.org/D110485).
+#elif FMT_MSC_VERSION >= 1929 && !FMT_CLANG_VERSION
+#  define FMT_NO_UNIQUE_ADDRESS [[msvc::no_unique_address]]
+#endif
+#ifndef FMT_NO_UNIQUE_ADDRESS
+#  define FMT_NO_UNIQUE_ADDRESS
+#endif
+
 #if FMT_HAS_CPP17_ATTRIBUTE(fallthrough)
 #  define FMT_FALLTHROUGH [[fallthrough]]
 #elif defined(__clang__)
@@ -2608,7 +2622,7 @@ class context {
  private:
   appender out_;
   format_args args_;
-  detail::locale_ref loc_;  // DEPRECATED! Should be replaced with a base class.
+  FMT_NO_UNIQUE_ADDRESS detail::locale_ref loc_;
 
  public:
   /// The character type for the output.
diff --git a/include/fmt/format.h b/include/fmt/format.h
index 9ee6d683..d1b83d18 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -151,20 +151,6 @@ FMT_END_NAMESPACE
 #  endif  // FMT_USE_EXCEPTIONS
 #endif    // FMT_THROW
 
-#ifdef FMT_NO_UNIQUE_ADDRESS
-// Use the provided definition.
-#elif FMT_CPLUSPLUS < 202002L
-// Not supported.
-#elif FMT_HAS_CPP_ATTRIBUTE(no_unique_address)
-#  define FMT_NO_UNIQUE_ADDRESS [[no_unique_address]]
-// VS2019 v16.10 and later except clang-cl (https://reviews.llvm.org/D110485).
-#elif FMT_MSC_VERSION >= 1929 && !FMT_CLANG_VERSION
-#  define FMT_NO_UNIQUE_ADDRESS [[msvc::no_unique_address]]
-#endif
-#ifndef FMT_NO_UNIQUE_ADDRESS
-#  define FMT_NO_UNIQUE_ADDRESS
-#endif
-
 // Defining FMT_REDUCE_INT_INSTANTIATIONS to 1, will reduce the number of
 // integer formatter template instantiations to just one by only using the
 // largest integer type. This results in a reduction in binary size but will