diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/moveable.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/moveable.cc
index 5de2a5f9330..3ba39ec432d 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/moveable.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/moveable.cc
@@ -35,7 +35,9 @@ void test01()
 
   std::string c(std::move(b));
   VERIFY( c.size() == 1 && c[0] == '1' );
-  VERIFY( b.size() == 0 );
+#if ! _GLIBCXX_FULLY_DYNAMIC_STRING
+  VERIFY( b.size() == 0 ); // not guaranteed by the standard
+#endif
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/moveable2.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/moveable2.cc
index fe91c5ab539..5804ccb6bf8 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/moveable2.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/moveable2.cc
@@ -44,7 +44,9 @@ void test01()
 
   tstring c(std::move(b));
   VERIFY( c.size() == 1 && c[0] == '1' );
-  VERIFY( b.size() == 0 );
+#if ! _GLIBCXX_FULLY_DYNAMIC_STRING
+  VERIFY( b.size() == 0 ); // not guaranteed by the standard
+#endif
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/moveable2_c++17.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/moveable2_c++17.cc
index 1caedcccfce..59d1d775134 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/moveable2_c++17.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/moveable2_c++17.cc
@@ -42,7 +42,9 @@ void test01()
 
   tstring c(std::move(b));
   VERIFY( c.size() == 1 && c[0] == '1' );
-  VERIFY( b.size() == 0 );
+#if ! _GLIBCXX_FULLY_DYNAMIC_STRING
+  VERIFY( b.size() == 0 ); // not guaranteed by the standard
+#endif
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/moveable.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/moveable.cc
index d05afb7d466..67e25de2916 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/moveable.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/moveable.cc
@@ -35,7 +35,9 @@ void test01()
 
   std::wstring c(std::move(b));
   VERIFY( c.size() == 1 && c[0] == L'1' );
-  VERIFY( b.size() == 0 );
+#if ! _GLIBCXX_FULLY_DYNAMIC_STRING
+  VERIFY( b.size() == 0 ); // not guaranteed by the standard
+#endif
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/moveable2.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/moveable2.cc
index e301984612d..c72eb9bfddb 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/moveable2.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/moveable2.cc
@@ -44,7 +44,9 @@ void test01()
 
   twstring c(std::move(b));
   VERIFY( c.size() == 1 && c[0] == L'1' );
-  VERIFY( b.size() == 0 );
+#if ! _GLIBCXX_FULLY_DYNAMIC_STRING
+  VERIFY( b.size() == 0 ); // not guaranteed by the standard
+#endif
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/moveable2_c++17.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/moveable2_c++17.cc
index d3e4744ff34..6a2bc2714b5 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/moveable2_c++17.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/moveable2_c++17.cc
@@ -42,7 +42,9 @@ void test01()
 
   tstring c(std::move(b));
   VERIFY( c.size() == 1 && c[0] == L'1' );
-  VERIFY( b.size() == 0 );
+#if ! _GLIBCXX_FULLY_DYNAMIC_STRING
+  VERIFY( b.size() == 0 ); // not guaranteed by the standard
+#endif
 }
 
 int main()
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/char/87749.cc b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/char/87749.cc
index 87d8c2f4068..6a3ed55f557 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/char/87749.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/char/87749.cc
@@ -71,8 +71,8 @@ int main()
 
   string s = "PR libstdc++/87749 a string that is longer than a short string";
   const auto ptr = s.c_str();
-  oom = true;
   string ss;
+  oom = true;
   ss = std::move(s); // allocators are equal, should not allocate new storage
   VERIFY( ss.c_str() == ptr );
 }
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/wchar_t/87749.cc b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/wchar_t/87749.cc
index 4d744f8a411..536ca6153d3 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/wchar_t/87749.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/modifiers/assign/wchar_t/87749.cc
@@ -72,8 +72,8 @@ int main()
 
   string s = L"PR libstdc++/87749 a string that is longer than a short string";
   const auto ptr = s.c_str();
-  oom = true;
   string ss;
+  oom = true;
   ss = std::move(s); // allocators are equal, should not allocate new storage
   VERIFY( ss.c_str() == ptr );
 }
