diff --git a/libcxx/include/__chrono/ostream.h b/libcxx/include/__chrono/ostream.h
--- a/libcxx/include/__chrono/ostream.h
+++ b/libcxx/include/__chrono/ostream.h
@@ -13,7 +13,7 @@
 #include <__chrono/day.h>
 #include <__chrono/statically_widen.h>
 #include <__config>
-#include <format>
+#include <__format/format_functions.h>
 #include <ostream>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/test/libcxx/transitive_includes/cxx20/expected.chrono b/libcxx/test/libcxx/transitive_includes/cxx20/expected.chrono
--- a/libcxx/test/libcxx/transitive_includes/cxx20/expected.chrono
+++ b/libcxx/test/libcxx/transitive_includes/cxx20/expected.chrono
@@ -20,7 +20,6 @@
 cwchar
 cwctype
 exception
-format
 functional
 initializer_list
 ios
diff --git a/libcxx/test/libcxx/transitive_includes/cxx2b/expected.chrono b/libcxx/test/libcxx/transitive_includes/cxx2b/expected.chrono
--- a/libcxx/test/libcxx/transitive_includes/cxx2b/expected.chrono
+++ b/libcxx/test/libcxx/transitive_includes/cxx2b/expected.chrono
@@ -18,7 +18,6 @@
 cwchar
 cwctype
 exception
-format
 initializer_list
 ios
 iosfwd