diff --git a/src/util/StringCompare.cxx b/src/util/StringCompare.cxx
index 643edff40..a02887cec 100644
--- a/src/util/StringCompare.cxx
+++ b/src/util/StringCompare.cxx
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2018 Max Kellermann <max.kellermann@gmail.com>
+ * Copyright 2013-2020 Max Kellermann <max.kellermann@gmail.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
diff --git a/src/util/StringCompare.hxx b/src/util/StringCompare.hxx
index b667b8c80..436e45c3a 100644
--- a/src/util/StringCompare.hxx
+++ b/src/util/StringCompare.hxx
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2018 Max Kellermann <max.kellermann@gmail.com>
+ * Copyright 2013-2020 Max Kellermann <max.kellermann@gmail.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -38,6 +38,8 @@
 #include "WStringCompare.hxx"
 #endif
 
+#include <string_view>
+
 gcc_pure gcc_nonnull_all
 static inline bool
 StringIsEmpty(const char *string) noexcept
diff --git a/src/util/WStringCompare.cxx b/src/util/WStringCompare.cxx
index ea67f3d2d..97f17faaa 100644
--- a/src/util/WStringCompare.cxx
+++ b/src/util/WStringCompare.cxx
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2019 Max Kellermann <max.kellermann@gmail.com>
+ * Copyright 2013-2020 Max Kellermann <max.kellermann@gmail.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
diff --git a/src/util/WStringCompare.hxx b/src/util/WStringCompare.hxx
index 6b3c60350..d7c4d0bfe 100644
--- a/src/util/WStringCompare.hxx
+++ b/src/util/WStringCompare.hxx
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2018 Max Kellermann <max.kellermann@gmail.com>
+ * Copyright 2013-2020 Max Kellermann <max.kellermann@gmail.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -34,6 +34,8 @@
 #include "WStringAPI.hxx"
 #include "Compiler.h"
 
+#include <string_view>
+
 #include <wchar.h>
 
 gcc_pure gcc_nonnull_all