diff --git a/libcxx/include/span b/libcxx/include/span
--- a/libcxx/include/span
+++ b/libcxx/include/span
@@ -129,11 +129,10 @@
 */
 
 #include <__config>
-#include <cstddef>      // for ptrdiff_t
-#include <iterator>     // for iterators
 #include <array>        // for array
-#include <type_traits>  // for remove_cv, etc
 #include <cstddef>      // for byte
+#include <iterator>     // for iterators
+#include <type_traits>  // for remove_cv, etc
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header