diff --git a/src/rp2_common/pico_standard_link/new_delete.cpp b/src/rp2_common/pico_standard_link/new_delete.cpp
index a7dd3b0..c122dc0 100644
--- a/src/rp2_common/pico_standard_link/new_delete.cpp
+++ b/src/rp2_common/pico_standard_link/new_delete.cpp
@@ -17,10 +17,16 @@ void *operator new[](std::size_t n) {
     return std::malloc(n);
 }
 
-void operator delete(void *p, __unused std::size_t n) noexcept { std::free(p); }
-
 void operator delete(void *p) { std::free(p); }
 
 void operator delete[](void *p) noexcept { std::free(p); }
 
+#if __cpp_sized_deallocation
+
+void operator delete(void *p, __unused std::size_t n) noexcept { std::free(p); }
+
+void operator delete[](void *p, __unused std::size_t n) noexcept { std::free(p); }
+
+#endif
+
 #endif