diff --git a/test/unit.cpp b/test/unit.cpp
index dcf616933d..75753c9927 100644
--- a/test/unit.cpp
+++ b/test/unit.cpp
@@ -9228,8 +9228,11 @@ TEST_CASE("concepts")
 
         SECTION("CopyAssignable")
         {
+// STL iterators used by json::iterator don't pass this test in Debug mode
+#if !defined(_MSC_VER) || (_ITERATOR_DEBUG_LEVEL == 0)
             CHECK(std::is_nothrow_copy_assignable<json::iterator>::value);
             CHECK(std::is_nothrow_copy_assignable<json::const_iterator>::value);
+#endif
         }
 
         SECTION("Destructible")