diff --git a/libcxx/test/std/thread/futures/futures.future_error/what.pass.cpp b/libcxx/test/std/thread/futures/futures.future_error/what.pass.cpp
--- a/libcxx/test/std/thread/futures/futures.future_error/what.pass.cpp
+++ b/libcxx/test/std/thread/futures/futures.future_error/what.pass.cpp
@@ -24,31 +24,46 @@
 // const char* what() const throw();
 
 #include <future>
-#include <cstring>
+#include <string>
 #include <cassert>
 
 #include "test_macros.h"
 
 int main(int, char**)
 {
+    std::string s[4];
+
     {
         std::future_error f(std::make_error_code(std::future_errc::broken_promise));
-        LIBCPP_ASSERT(std::strcmp(f.what(), "The associated promise has been destructed prior "
-                      "to the associated state becoming ready.") == 0);
+        s[0] = std::string(f.what());
+        LIBCPP_ASSERT(s[0] == "The associated promise has been destructed prior "
+                      "to the associated state becoming ready.");
     }
     {
         std::future_error f(std::make_error_code(std::future_errc::future_already_retrieved));
-        LIBCPP_ASSERT(std::strcmp(f.what(), "The future has already been retrieved from "
-                      "the promise or packaged_task.") == 0);
+        s[1] = std::string(f.what());
+        LIBCPP_ASSERT(s[1] == "The future has already been retrieved from "
+                      "the promise or packaged_task.");
     }
     {
         std::future_error f(std::make_error_code(std::future_errc::promise_already_satisfied));
-        LIBCPP_ASSERT(std::strcmp(f.what(), "The state of the promise has already been set.") == 0);
+        s[2] = std::string(f.what());
+        LIBCPP_ASSERT(s[2] == "The state of the promise has already been set.");
     }
     {
         std::future_error f(std::make_error_code(std::future_errc::no_state));
-        LIBCPP_ASSERT(std::strcmp(f.what(), "Operation not permitted on an object without "
-                      "an associated state.") == 0);
+        s[3] = std::string(f.what());
+        LIBCPP_ASSERT(s[3] == "Operation not permitted on an object without "
+                      "an associated state.");
+    }
+
+    for ( int i = 0; i < 4; i++ )
+    {
+        assert(s[i].length() != 0);
+        for ( int j = i+1; j < 4; j++ )
+        {
+            assert(s[i].compare(s[j]) != 0);
+        }
     }
 
   return 0;