diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/append/wchar_t/1.cc b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/append/wchar_t/1.cc
index bb2d682de8ecab8513df2a8bef0b15e421ee0b67..684209f143ee91508b874393893a2fe6c9027c6a 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/append/wchar_t/1.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/append/wchar_t/1.cc
@@ -117,7 +117,7 @@ void test01(void)
   VERIFY( str06 == L"corpus, corpus" );
 
   str06 = str02;
-  str06.append(L"corpus, ", 12);
+  str06.append(L"corpus, ", 9); // n=9 includes null terminator
   VERIFY( str06 != L"corpus, corpus, " );
 
 
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/compare/wchar_t/1.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/compare/wchar_t/1.cc
index 27836f8e6fbe4e7590701c9f02d82923314ebf8d..6f2113fb16ac73e7a59b21adaf0f9bc14721735b 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/operations/compare/wchar_t/1.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/compare/wchar_t/1.cc
@@ -81,8 +81,8 @@ test01()
   test_value(wcsncmp(str_1.data(), str_0.data(), 6), z);
   test_value(wcsncmp(str_1.data(), str_0.data(), 14), lt);
   test_value(wmemcmp(str_1.data(), str_0.data(), 6), z);
-  test_value(wmemcmp(str_1.data(), str_0.data(), 14), lt);
-  test_value(wmemcmp(L"costa marbella", L"costa rica", 14), lt);
+  test_value(wmemcmp(str_1.data(), str_0.data(), 10), lt);
+  test_value(wmemcmp(L"costa marbella", L"costa rica", 10), lt);
 
   // int compare(const basic_string& str) const;
   test_value(str_0.compare(str_1), gt); //because r>m
diff --git a/libstdc++-v3/testsuite/experimental/string_view/operations/compare/wchar_t/1.cc b/libstdc++-v3/testsuite/experimental/string_view/operations/compare/wchar_t/1.cc
index db523e6a83cc2fb9d01fb757db32c2191051f2bc..20bb030970b447d297f22fa55a7e689fefeadcb6 100644
--- a/libstdc++-v3/testsuite/experimental/string_view/operations/compare/wchar_t/1.cc
+++ b/libstdc++-v3/testsuite/experimental/string_view/operations/compare/wchar_t/1.cc
@@ -81,8 +81,8 @@ test01()
   test_value(wcsncmp(str_1.data(), str_0.data(), 6), z);
   test_value(wcsncmp(str_1.data(), str_0.data(), 14), lt);
   test_value(wmemcmp(str_1.data(), str_0.data(), 6), z);
-  test_value(wmemcmp(str_1.data(), str_0.data(), 14), lt);
-  test_value(wmemcmp(L"costa marbella", L"costa rica", 14), lt);
+  test_value(wmemcmp(str_1.data(), str_0.data(), 10), lt);
+  test_value(wmemcmp(L"costa marbella", L"costa rica", 10), lt);
 
   // int compare(const basic_string_view& str) const;
   test_value(str_0.compare(str_1), gt); //because r>m