diff --git a/test/support/msvc_stdlib_force_include.hpp b/test/support/msvc_stdlib_force_include.hpp
index fcf64d7..fd8438f 100644
--- a/test/support/msvc_stdlib_force_include.hpp
+++ b/test/support/msvc_stdlib_force_include.hpp
@@ -72,8 +72,9 @@
     // atomic_is_lock_free.pass.cpp needs this VS 2015 Update 2 fix.
     #define _ENABLE_ATOMIC_ALIGNMENT_FIX
 
-    // Silence warnings about features that are deprecated in C++17.
+    // Silence warnings about features that are deprecated in C++17 and C++20.
     #define _SILENCE_ALL_CXX17_DEPRECATION_WARNINGS
+    #define _SILENCE_ALL_CXX20_DEPRECATION_WARNINGS
 #endif // _LIBCXX_IN_DEVCRT
 
 #include <ciso646>