diff --git a/libcxx/test/std/localization/locale.categories/category.collate/locale.collate.byname/compare.pass.cpp b/libcxx/test/std/localization/locale.categories/category.collate/locale.collate.byname/compare.pass.cpp
index 69af9ac1b7bf..09009ceaaae2 100644
--- a/libcxx/test/std/localization/locale.categories/category.collate/locale.collate.byname/compare.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/category.collate/locale.collate.byname/compare.pass.cpp
@@ -7,6 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// REQUIRES: locale.en_US.UTF-8
+
 // <locale>
 
 // template <class charT> class collate_byname
diff --git a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/tolower_1.pass.cpp b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/tolower_1.pass.cpp
index c2eeea820ba0..741f47f4380c 100644
--- a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/tolower_1.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/tolower_1.pass.cpp
@@ -7,6 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// REQUIRES: locale.en_US.UTF-8
+
 // <locale>
 
 // template <class charT> class ctype_byname;
diff --git a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/tolower_many.pass.cpp b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/tolower_many.pass.cpp
index b2577e323a2d..bf1cb64b22c0 100644
--- a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/tolower_many.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/tolower_many.pass.cpp
@@ -7,6 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// REQUIRES: locale.en_US.UTF-8
+
 // <locale>
 
 // template <class charT> class ctype_byname;
diff --git a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/toupper_1.pass.cpp b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/toupper_1.pass.cpp
index 8611293b84aa..3044ba1897fc 100644
--- a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/toupper_1.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/toupper_1.pass.cpp
@@ -7,6 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// REQUIRES: locale.en_US.UTF-8
+
 // <locale>
 
 // template <class charT> class ctype_byname;
diff --git a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/toupper_many.pass.cpp b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/toupper_many.pass.cpp
index d23a29273e2b..be6ba4c3e908 100644
--- a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/toupper_many.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/toupper_many.pass.cpp
@@ -7,6 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// REQUIRES: locale.en_US.UTF-8
+
 // <locale>
 
 // template <class charT> class ctype_byname;
diff --git a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/widen_1.pass.cpp b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/widen_1.pass.cpp
index 320e08db26e0..e5c49defa11f 100644
--- a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/widen_1.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/widen_1.pass.cpp
@@ -7,6 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// REQUIRES: locale.en_US.UTF-8
+
 // <locale>
 
 // template <class charT> class ctype_byname;
diff --git a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/widen_many.pass.cpp b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/widen_many.pass.cpp
index b46ae32237b7..c16974a2414a 100644
--- a/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/widen_many.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/category.ctype/locale.ctype.byname/widen_many.pass.cpp
@@ -7,6 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// REQUIRES: locale.en_US.UTF-8
+
 // <locale>
 
 // template <class charT> class ctype_byname;