diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 8501a66fffa8..d8308c3f6f44 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,5 +1,8 @@
 2017-12-01  Jonathan Wakely  <jwakely@redhat.com>
 
+	* include/bits/locale_facets_nonio.tcc (money_get::_M_extract): Add
+	fallthrough comment.
+
 	* include/bits/node_handle.h (_Node_handle_common::operator=)
 	(_Node_handle_common::_M_swap): Add braces around debug assertions.
 
diff --git a/libstdc++-v3/include/bits/locale_facets_nonio.tcc b/libstdc++-v3/include/bits/locale_facets_nonio.tcc
index a449c41e6b8d..135dd0b9d8fc 100644
--- a/libstdc++-v3/include/bits/locale_facets_nonio.tcc
+++ b/libstdc++-v3/include/bits/locale_facets_nonio.tcc
@@ -282,6 +282,7 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11
 		  ++__beg;
 		else
 		  __testvalid = false;
+		// fallthrough
 	      case money_base::none:
 		// Only if not at the end of the pattern.
 		if (__i != 3)