diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 2ac56cc748e2..d7a9dbb6ce3a 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,5 +1,7 @@
 2018-07-25  Jonathan Wakely  <jwakely@redhat.com>
 
+	* include/experimental/memory_resource: Include <cstddef> header.
+
 	* acinclude.m4 (glibcxx_SUBDIRS): Add src/c++17.
 	* src/Makefile.am: Add comment.
 	* src/c++17/Makefile.in: Regenerate.
diff --git a/libstdc++-v3/include/experimental/memory_resource b/libstdc++-v3/include/experimental/memory_resource
index 7ce64457a115..61c9ce0a14ad 100644
--- a/libstdc++-v3/include/experimental/memory_resource
+++ b/libstdc++-v3/include/experimental/memory_resource
@@ -32,7 +32,8 @@
 #include <memory>			// align, uses_allocator, __uses_alloc
 #include <experimental/utility>		// pair, experimental::erased_type
 #include <atomic>			// atomic
-#include <new>
+#include <new>				// placement new
+#include <cstddef>			// max_align_t
 #include <ext/new_allocator.h>
 #include <debug/assertions.h>