diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 9b876d0307d..e752285bdb2 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,7 @@
+2019-03-08  Jonathan Wakely  <jwakely@redhat.com>
+
+	* include/bits/fs_path.h (path::format): Add fixed underlying type.
+
 2019-03-08  François Dumont  <fdumont@gcc.gnu.org>
 
 	PR libstdc++/89477
diff --git a/libstdc++-v3/include/bits/fs_path.h b/libstdc++-v3/include/bits/fs_path.h
index 077045e6c78..96033f68c36 100644
--- a/libstdc++-v3/include/bits/fs_path.h
+++ b/libstdc++-v3/include/bits/fs_path.h
@@ -166,7 +166,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
 #endif
     typedef std::basic_string<value_type>	string_type;
 
-    enum format { native_format, generic_format, auto_format };
+    enum format : unsigned char { native_format, generic_format, auto_format };
 
     // constructors and destructor