1 files changed, 14 insertions, 0 deletions
diff --git a/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/generic_category.pass.cpp b/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/generic_category.pass.cpp
index 972299936ddf..65ecc4921212 100644
--- a/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/generic_category.pass.cpp
+++ b/test/std/diagnostics/syserr/syserr.errcat/syserr.errcat.objects/generic_category.pass.cpp
@@ -16,10 +16,24 @@
 #include <system_error>
 #include <cassert>
 #include <string>
+#include <cerrno>
+
+#include "test_macros.h"
+
+void test_message_for_bad_value() {
+    errno = E2BIG; // something that message will never generate
+    const std::error_category& e_cat1 = std::generic_category();
+    const std::string msg = e_cat1.message(-1);
+    LIBCPP_ASSERT(msg == "Unknown error -1");
+    assert(errno == E2BIG);
+}
 
 int main()
 {
     const std::error_category& e_cat1 = std::generic_category();
     std::string m1 = e_cat1.name();
     assert(m1 == "generic");
+    {
+        test_message_for_bad_value();
+    }
 }