diff --git a/include/wil/resource.h b/include/wil/resource.h
index c2ff77e..ca7db78 100644
--- a/include/wil/resource.h
+++ b/include/wil/resource.h
@@ -1245,6 +1245,7 @@ public:
         {
             reset_array(ElementDeleter());
 
+#if __cpp_if_constexpr >= 201606L
             // If the deleter has overloads that can accept either just the pointer, or the pointer and size, we prioritize the
             // pointer-only version, since that is the version we initially supported. And if we can't invoke it with either
             // parameter set, we'll allow the compiler to still try to invoke the pointer-only version and cause it to emit an
@@ -1257,6 +1258,10 @@ public:
             {
                 ArrayDeleter()(m_ptr, m_size);
             }
+#else
+            // No C++17 support... fall back to the old behavior and assume just a pointer
+            ArrayDeleter()(m_ptr);
+#endif
 
             m_ptr = nullptr;
             m_size = size_type{};
@@ -8322,10 +8327,12 @@ namespace details
     {
     };
 
+#if __cpp_lib_scoped_lock >= 201703L
     template <typename TMutex>
     struct lock_proof_traits<std::scoped_lock<TMutex>> : exclusive_lock_proof
     {
     };
+#endif
 } // namespace details
 /// @endcond