diff --git a/libstdc++-v3/testsuite/22_locale/conversions/buffer/1.cc b/libstdc++-v3/testsuite/22_locale/conversions/buffer/1.cc
index 2d5c09449ca..9db7fce7241 100644
--- a/libstdc++-v3/testsuite/22_locale/conversions/buffer/1.cc
+++ b/libstdc++-v3/testsuite/22_locale/conversions/buffer/1.cc
@@ -31,12 +31,11 @@ template<typename Elem>
 using buf_conv = std::wbuffer_convert<cvt<Elem>, Elem>;
 
 using std::string;
-using std::stringstream;
 using std::wstring;
-using std::wstringstream;
 
 void test01()
 {
+#ifdef _GLIBCXX_USE_WCHAR_T
   buf_conv<wchar_t> buf;
   std::stringbuf sbuf;
   VERIFY( buf.rdbuf() == nullptr );
@@ -46,6 +45,7 @@ void test01()
 
   __gnu_test::implicitly_default_constructible test;
   test.operator()<buf_conv<wchar_t>>(); // P0935R0
+#endif
 }
 
 void test02()
@@ -53,7 +53,7 @@ void test02()
   std::stringbuf sbuf;
   buf_conv<char> buf(&sbuf);  // noconv
 
-  stringstream ss;
+  std::stringstream ss;
   ss.std::ios::rdbuf(&buf);
   string input = "King for a day...";
   ss << input << std::flush;
@@ -63,15 +63,17 @@ void test02()
 
 void test03()
 {
+#ifdef _GLIBCXX_USE_WCHAR_T
   std::stringbuf sbuf;
   buf_conv<wchar_t> buf(&sbuf);
 
-  wstringstream ss;
+  std::wstringstream ss;
   ss.std::wios::rdbuf(&buf);
   wstring input = L"Fool for a lifetime";
   ss << input << std::flush;
   string output = sbuf.str();
   VERIFY( output == "Fool for a lifetime" );
+#endif
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/22_locale/conversions/buffer/3.cc b/libstdc++-v3/testsuite/22_locale/conversions/buffer/3.cc
index 94aa43bbfdb..3e1d90ffe92 100644
--- a/libstdc++-v3/testsuite/22_locale/conversions/buffer/3.cc
+++ b/libstdc++-v3/testsuite/22_locale/conversions/buffer/3.cc
@@ -38,21 +38,37 @@ private:
   char c = 'a';
 };
 
-struct codecvt : std::codecvt<wchar_t, char, std::mbstate_t> { };
 
 void
 test01()
 {
+#ifdef _GLIBCXX_USE_WCHAR_T
+  struct codecvt : std::codecvt<wchar_t, char, std::mbstate_t> { };
   // https://gcc.gnu.org/ml/libstdc++/2017-11/msg00022.html
   streambuf sb;
   std::wbuffer_convert<codecvt> conv(&sb);
   VERIFY( sb.in_avail() == 0 );
   wchar_t c = conv.sgetc();
   VERIFY( c == L'a' );
+#endif
+}
+
+
+void
+test02()
+{
+  struct codecvt : std::codecvt<char16_t, char, std::mbstate_t> { };
+  // https://gcc.gnu.org/ml/libstdc++/2017-11/msg00022.html
+  streambuf sb;
+  std::wbuffer_convert<codecvt, char16_t> conv(&sb);
+  VERIFY( sb.in_avail() == 0 );
+  char16_t c = conv.sgetc();
+  VERIFY( c == u'a' );
 }
 
 int
 main()
 {
   test01();
+  test02();
 }
diff --git a/libstdc++-v3/testsuite/22_locale/conversions/string/1.cc b/libstdc++-v3/testsuite/22_locale/conversions/string/1.cc
index 0016910441e..b5132dadce4 100644
--- a/libstdc++-v3/testsuite/22_locale/conversions/string/1.cc
+++ b/libstdc++-v3/testsuite/22_locale/conversions/string/1.cc
@@ -51,6 +51,7 @@ void test01()
 
 void test02()
 {
+#ifdef _GLIBCXX_USE_WCHAR_T
   typedef str_conv<wchar_t> wsc;
   wsc c;
   string input = "Fool for a lifetime";
@@ -71,6 +72,7 @@ void test02()
 
   __gnu_test::implicitly_default_constructible test;
   test.operator()<wsc>(); // P0935R0
+#endif
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/27_io/filesystem/path/generic/generic_string.cc b/libstdc++-v3/testsuite/27_io/filesystem/path/generic/generic_string.cc
index 85d564e1592..4a603e23067 100644
--- a/libstdc++-v3/testsuite/27_io/filesystem/path/generic/generic_string.cc
+++ b/libstdc++-v3/testsuite/27_io/filesystem/path/generic/generic_string.cc
@@ -69,7 +69,9 @@ test03()
     // A path constructed from the generic format string should compare equal
     // to the original, because they represent the same path.
     VERIFY( path(p.generic_string()) == p );
+#ifdef _GLIBCXX_USE_WCHAR_T
     VERIFY( path(p.generic_wstring()) == p );
+#endif
     VERIFY( path(p.generic_u8string()) == p );
     VERIFY( path(p.generic_u16string()) == p );
     VERIFY( path(p.generic_u32string()) == p );
@@ -80,7 +82,9 @@ test03()
     // A path constructed from the generic format string should compare equal
     // to the original, because they represent the same path.
     VERIFY( path(p.generic_string()) == p );
+#ifdef _GLIBCXX_USE_WCHAR_T
     VERIFY( path(p.generic_wstring()) == p );
+#endif
     VERIFY( path(p.generic_u8string()) == p );
     VERIFY( path(p.generic_u16string()) == p );
     VERIFY( path(p.generic_u32string()) == p );
diff --git a/libstdc++-v3/testsuite/27_io/filesystem/path/modifiers/make_preferred.cc b/libstdc++-v3/testsuite/27_io/filesystem/path/modifiers/make_preferred.cc
index 8f9e720f302..d21f1796798 100644
--- a/libstdc++-v3/testsuite/27_io/filesystem/path/modifiers/make_preferred.cc
+++ b/libstdc++-v3/testsuite/27_io/filesystem/path/modifiers/make_preferred.cc
@@ -45,7 +45,11 @@ struct checker<wchar_t, L'\\'>
 {
   static void check()
   {
+#ifdef _GLIBCXX_USE_WCHAR_T
     VERIFY( path("foo/bar").make_preferred() == L"foo\\bar" );
+#else
+    VERIFY( ! "filesystem::path needs --enable-wchar_t on this target" );
+#endif
   }
 };
 
diff --git a/libstdc++-v3/testsuite/27_io/filesystem/path/native/alloc.cc b/libstdc++-v3/testsuite/27_io/filesystem/path/native/alloc.cc
index fb0b75d2efc..87a59b6735d 100644
--- a/libstdc++-v3/testsuite/27_io/filesystem/path/native/alloc.cc
+++ b/libstdc++-v3/testsuite/27_io/filesystem/path/native/alloc.cc
@@ -41,9 +41,11 @@ test01()
   VERIFY( str8.get_allocator() == alloc<char8_t>(1) );
 #endif
 
+#ifdef _GLIBCXX_USE_WCHAR_T
   auto strw = p.string<wchar_t>(alloc<wchar_t>(2));
   VERIFY( strw == L"" );
   VERIFY( strw.get_allocator() == alloc<wchar_t>(2) );
+#endif
 
   auto str16 = p.string<char16_t>(alloc<char16_t>(3));
   VERIFY( str16 == u"" );
@@ -70,9 +72,11 @@ test02()
   VERIFY( str8.get_allocator() == alloc<char8_t>(1) );
 #endif
 
+#ifdef _GLIBCXX_USE_WCHAR_T
   auto strw = p.string<wchar_t>(alloc<wchar_t>(2));
   VERIFY( strw == L"abcdefghijklmnopqrstuvwxyz" );
   VERIFY( strw.get_allocator() == alloc<wchar_t>(2) );
+#endif
 
   auto str16 = p.string<char16_t>(alloc<char16_t>(3));
   VERIFY( str16 == u"abcdefghijklmnopqrstuvwxyz" );
diff --git a/libstdc++-v3/testsuite/27_io/filesystem/path/native/string-char8_t.cc b/libstdc++-v3/testsuite/27_io/filesystem/path/native/string-char8_t.cc
index df0bb5f0156..94421292d27 100644
--- a/libstdc++-v3/testsuite/27_io/filesystem/path/native/string-char8_t.cc
+++ b/libstdc++-v3/testsuite/27_io/filesystem/path/native/string-char8_t.cc
@@ -50,9 +50,11 @@ test02()
   VERIFY( str == "abc" );
   VERIFY( str == p.string() );
 
+#ifdef _GLIBCXX_USE_WCHAR_T
   auto strw = p.string<wchar_t>();
   VERIFY( strw == L"abc" );
   VERIFY( strw == p.wstring() );
+#endif
 
 #ifdef _GLIBCXX_USE_CHAR8_T
   auto str8 = p.string<char8_t>();
diff --git a/libstdc++-v3/testsuite/27_io/filesystem/path/native/string.cc b/libstdc++-v3/testsuite/27_io/filesystem/path/native/string.cc
index b4f802d739f..a61f78ad0c4 100644
--- a/libstdc++-v3/testsuite/27_io/filesystem/path/native/string.cc
+++ b/libstdc++-v3/testsuite/27_io/filesystem/path/native/string.cc
@@ -48,9 +48,11 @@ test02()
   VERIFY( str == "abc" );
   VERIFY( str == p.string() );
 
+#ifdef _GLIBCXX_USE_WCHAR_T
   auto strw = p.string<wchar_t>();
   VERIFY( strw == L"abc" );
   VERIFY( strw == p.wstring() );
+#endif
 
   auto str16 = p.string<char16_t>();
   VERIFY( str16 == u"abc" );
diff --git a/libstdc++-v3/testsuite/28_regex/algorithms/regex_match/extended/wstring_locale.cc b/libstdc++-v3/testsuite/28_regex/algorithms/regex_match/extended/wstring_locale.cc
index bd030373e71..a24ee630797 100644
--- a/libstdc++-v3/testsuite/28_regex/algorithms/regex_match/extended/wstring_locale.cc
+++ b/libstdc++-v3/testsuite/28_regex/algorithms/regex_match/extended/wstring_locale.cc
@@ -35,12 +35,14 @@ using namespace std;
 void
 test01()
 {
+#ifdef _GLIBCXX_USE_WCHAR_T
   std::wstring str2 = L"ÜBER";
   std::wregex re2;
   re2.imbue(std::locale("de_DE.UTF-8"));
   re2.assign(L"[[:upper:]]*", std::regex::extended);
   std::wsmatch m2;
   VERIFY(regex_match_debug(str2, m2, re2));
+#endif
 }
 
 int
diff --git a/libstdc++-v3/testsuite/experimental/filesystem/path/generic/generic_string.cc b/libstdc++-v3/testsuite/experimental/filesystem/path/generic/generic_string.cc
index d8e35ee8707..26d68c81b96 100644
--- a/libstdc++-v3/testsuite/experimental/filesystem/path/generic/generic_string.cc
+++ b/libstdc++-v3/testsuite/experimental/filesystem/path/generic/generic_string.cc
@@ -55,7 +55,9 @@ test03()
     // A path constructed from the generic format string should compare equal
     // to the original, because they represent the same path.
     VERIFY( path(p.generic_string()) == p );
+#ifdef _GLIBCXX_USE_WCHAR_T
     VERIFY( path(p.generic_wstring()) == p );
+#endif
     VERIFY( path(p.generic_u8string()) == p );
     VERIFY( path(p.generic_u16string()) == p );
     VERIFY( path(p.generic_u32string()) == p );
diff --git a/libstdc++-v3/testsuite/experimental/filesystem/path/native/alloc.cc b/libstdc++-v3/testsuite/experimental/filesystem/path/native/alloc.cc
index 591ebae263b..04426480311 100644
--- a/libstdc++-v3/testsuite/experimental/filesystem/path/native/alloc.cc
+++ b/libstdc++-v3/testsuite/experimental/filesystem/path/native/alloc.cc
@@ -43,9 +43,11 @@ test01()
   VERIFY( str8.get_allocator() == alloc<char8_t>(1) );
 #endif
 
+#ifdef _GLIBCXX_USE_WCHAR_T
   auto strw = p.string<wchar_t>(alloc<wchar_t>(2));
   VERIFY( strw == L"" );
   VERIFY( strw.get_allocator() == alloc<wchar_t>(2) );
+#endif
 
   auto str16 = p.string<char16_t>(alloc<char16_t>(3));
   VERIFY( str16 == u"" );
@@ -72,9 +74,11 @@ test02()
   VERIFY( str8.get_allocator() == alloc<char8_t>(1) );
 #endif
 
+#ifdef _GLIBCXX_USE_WCHAR_T
   auto strw = p.string<wchar_t>(alloc<wchar_t>(2));
   VERIFY( strw == L"abcdefghijklmnopqrstuvwxyz" );
   VERIFY( strw.get_allocator() == alloc<wchar_t>(2) );
+#endif
 
   auto str16 = p.string<char16_t>(alloc<char16_t>(3));
   VERIFY( str16 == u"abcdefghijklmnopqrstuvwxyz" );
diff --git a/libstdc++-v3/testsuite/experimental/filesystem/path/native/string-char8_t.cc b/libstdc++-v3/testsuite/experimental/filesystem/path/native/string-char8_t.cc
index d8dc1f81e50..9775fe89518 100644
--- a/libstdc++-v3/testsuite/experimental/filesystem/path/native/string-char8_t.cc
+++ b/libstdc++-v3/testsuite/experimental/filesystem/path/native/string-char8_t.cc
@@ -50,9 +50,11 @@ test02()
   VERIFY( str == u"abc" );
   VERIFY( str == p.string() );
 
+#ifdef _GLIBCXX_USE_WCHAR_T
   auto strw = p.string<wchar_t>();
   VERIFY( strw == L"abc" );
   VERIFY( strw == p.wstring() );
+#endif
 
 #ifdef _GLIBCXX_USE_CHAR8_T
   auto str8 = p.string<char8_t>();
diff --git a/libstdc++-v3/testsuite/experimental/filesystem/path/native/string.cc b/libstdc++-v3/testsuite/experimental/filesystem/path/native/string.cc
index 40f9bb9b4c3..d82a5390840 100644
--- a/libstdc++-v3/testsuite/experimental/filesystem/path/native/string.cc
+++ b/libstdc++-v3/testsuite/experimental/filesystem/path/native/string.cc
@@ -50,9 +50,11 @@ test02()
   VERIFY( str == u"abc" );
   VERIFY( str == p.string() );
 
+#ifdef _GLIBCXX_USE_WCHAR_T
   auto strw = p.string<wchar_t>();
   VERIFY( strw == L"abc" );
   VERIFY( strw == p.wstring() );
+#endif
 
   auto str16 = p.string<char16_t>();
   VERIFY( str16 == u"abc" );
