diff --git a/test/input.output/stream.buffers/streambuf/streambuf.cons/copy.pass.cpp b/test/input.output/stream.buffers/streambuf/streambuf.cons/copy.pass.cpp
index 2d05618a..ffad159f 100644
--- a/test/input.output/stream.buffers/streambuf/streambuf.cons/copy.pass.cpp
+++ b/test/input.output/stream.buffers/streambuf/streambuf.cons/copy.pass.cpp
@@ -70,7 +70,7 @@ int main()
         t.setp(&p1, &p3);
         test<wchar_t> t2 = t;
     }
-    std::locale::global(std::locale("en_US"));
+    std::locale::global(std::locale("en_US.UTF-8"));
     {
         test<char> t;
         test<char> t2 = t;
diff --git a/test/input.output/stream.buffers/streambuf/streambuf.cons/default.pass.cpp b/test/input.output/stream.buffers/streambuf/streambuf.cons/default.pass.cpp
index bc79cd33..f8f3b801 100644
--- a/test/input.output/stream.buffers/streambuf/streambuf.cons/default.pass.cpp
+++ b/test/input.output/stream.buffers/streambuf/streambuf.cons/default.pass.cpp
@@ -42,13 +42,13 @@ int main()
         test<wchar_t> t;
         assert(t.getloc().name() == "C");
     }
-    std::locale::global(std::locale("en_US"));
+    std::locale::global(std::locale("en_US.UTF-8"));
     {
         test<char> t;
-        assert(t.getloc().name() == "en_US");
+        assert(t.getloc().name() == "en_US.UTF-8");
     }
     {
         test<wchar_t> t;
-        assert(t.getloc().name() == "en_US");
+        assert(t.getloc().name() == "en_US.UTF-8");
     }
 }
diff --git a/test/input.output/stream.buffers/streambuf/streambuf.members/streambuf.locales/locales.pass.cpp b/test/input.output/stream.buffers/streambuf/streambuf.members/streambuf.locales/locales.pass.cpp
index 4bd58462..637fcbe8 100644
--- a/test/input.output/stream.buffers/streambuf/streambuf.members/streambuf.locales/locales.pass.cpp
+++ b/test/input.output/stream.buffers/streambuf/streambuf.members/streambuf.locales/locales.pass.cpp
@@ -26,7 +26,7 @@ struct test
 
     void imbue(const std::locale&)
     {
-        assert(this->getloc().name() == "en_US");
+        assert(this->getloc().name() == "en_US.UTF-8");
     }
 };
 
@@ -36,11 +36,11 @@ int main()
         test<char> t;
         assert(t.getloc().name() == "C");
     }
-    std::locale::global(std::locale("en_US"));
+    std::locale::global(std::locale("en_US.UTF-8"));
     {
         test<char> t;
-        assert(t.getloc().name() == "en_US");
-        assert(t.pubimbue(std::locale("fr_FR")).name() == "en_US");
-        assert(t.getloc().name() == "fr_FR");
+        assert(t.getloc().name() == "en_US.UTF-8");
+        assert(t.pubimbue(std::locale("fr_FR.UTF-8")).name() == "en_US.UTF-8");
+        assert(t.getloc().name() == "fr_FR.UTF-8");
     }
 }
diff --git a/test/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/assign.pass.cpp b/test/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/assign.pass.cpp
index 4a955cb2..def79eef 100644
--- a/test/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/assign.pass.cpp
+++ b/test/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/assign.pass.cpp
@@ -75,7 +75,7 @@ int main()
         test<wchar_t> t2;
         t2 = t;
     }
-    std::locale::global(std::locale("en_US"));
+    std::locale::global(std::locale("en_US.UTF-8"));
     {
         test<char> t;
         test<char> t2;
diff --git a/test/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/swap.pass.cpp b/test/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/swap.pass.cpp
index 833d2afc..0b33d336 100644
--- a/test/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/swap.pass.cpp
+++ b/test/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/swap.pass.cpp
@@ -85,7 +85,7 @@ int main()
         test<wchar_t> t2;
         swap(t2, t);
     }
-    std::locale::global(std::locale("en_US"));
+    std::locale::global(std::locale("en_US.UTF-8"));
     {
         test<char> t;
         test<char> t2;