diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -60,6 +60,10 @@
 -----------------------------------------
 - Clang won't search for coroutine_traits in std::experimental namespace any more.
   Clang will only search for std::coroutine_traits for coroutines then.
+- Clang no longer allows dereferencing of a ``void *`` as an extension. Clang 16
+  converted this to a default-error as ``-Wvoid-ptr-dereference``, as well as a
+  SFINAE error. This flag is still valid however, as it disables the equivalent
+  warning in C.
 
 ABI Changes in This Version
 ---------------------------
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -6981,9 +6981,8 @@
 def ext_typecheck_indirection_through_void_pointer : ExtWarn<
   "ISO C does not allow indirection on operand of type %0">,
   InGroup<VoidPointerDeref>;
-def ext_typecheck_indirection_through_void_pointer_cpp
-    : ExtWarn<"ISO C++ does not allow indirection on operand of type %0">,
-      InGroup<VoidPointerDeref>, DefaultError, SFINAEFailure;
+def err_typecheck_indirection_through_void_pointer_cpp
+    : Error<"indirection not permitted on operand of type %0">;
 def warn_indirection_through_null : Warning<
   "indirection of non-volatile null pointer will be deleted, not trap">,
   InGroup<NullDereference>;
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -14957,7 +14957,7 @@
     //   be a pointer to an object type, or a pointer to a function type
     LangOptions LO = S.getLangOpts();
     if (LO.CPlusPlus)
-      S.Diag(OpLoc, diag::ext_typecheck_indirection_through_void_pointer_cpp)
+      S.Diag(OpLoc, diag::err_typecheck_indirection_through_void_pointer_cpp)
           << OpTy << Op->getSourceRange();
     else if (!(LO.C99 && IsAfterAmp) && !S.isUnevaluatedContext())
       S.Diag(OpLoc, diag::ext_typecheck_indirection_through_void_pointer)
diff --git a/clang/test/CXX/temp/temp.decls/temp.class/temp.mem.func/p1inst.cpp b/clang/test/CXX/temp/temp.decls/temp.class/temp.mem.func/p1inst.cpp
--- a/clang/test/CXX/temp/temp.decls/temp.class/temp.mem.func/p1inst.cpp
+++ b/clang/test/CXX/temp/temp.decls/temp.class/temp.mem.func/p1inst.cpp
@@ -8,7 +8,7 @@
 
 template<typename T, typename U>
 void X0<T, U>::f(T *t, const U &u) {
-  *t = u; // expected-error{{indirection on operand of type 'void *'}} expected-error{{not assignable}}
+  *t = u; // expected-error{{indirection not permitted on operand of type 'void *'}} expected-error{{not assignable}}
 }
 
 void test_f(X0<float, int> xfi, X0<void, int> xvi, float *fp, void *vp, int i) {
diff --git a/clang/test/SemaCXX/decl-expr-ambiguity.cpp b/clang/test/SemaCXX/decl-expr-ambiguity.cpp
--- a/clang/test/SemaCXX/decl-expr-ambiguity.cpp
+++ b/clang/test/SemaCXX/decl-expr-ambiguity.cpp
@@ -35,7 +35,7 @@
   extern T f3();
   __typeof(*T()) f4(); // expected-warning {{empty parentheses interpreted as a function declaration}} expected-note {{replace parentheses with an initializer}}
   typedef void *V;
-  __typeof(*V()) f5(); // expected-error {{ISO C++ does not allow indirection on operand of type 'V' (aka 'void *')}}
+  __typeof(*V()) f5(); // expected-error {{indirection not permitted on operand of type 'V' (aka 'void *')}}
   T multi1,
     multi2(); // expected-warning {{empty parentheses interpreted as a function declaration}} expected-note {{replace parentheses with an initializer}}
   T(d)[5]; // expected-error {{redefinition of 'd'}}
diff --git a/clang/test/SemaCXX/disallow_void_deref.cpp b/clang/test/SemaCXX/disallow_void_deref.cpp
--- a/clang/test/SemaCXX/disallow_void_deref.cpp
+++ b/clang/test/SemaCXX/disallow_void_deref.cpp
@@ -1,8 +1,7 @@
-// RUN: %clang_cc1 -fsyntax-only -verify=enabled,sfinae -std=c++20 %s
-// RUN: %clang_cc1 -fsyntax-only -verify=sfinae -std=c++20 -Wno-void-ptr-dereference %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++20 %s
 
 void f(void* p) {
-  (void)*p; // enabled-error{{ISO C++ does not allow indirection on operand of type 'void *'}}
+  (void)*p; // expected-error{{indirection not permitted on operand of type 'void *'}}
 }
 
 template<class T>
@@ -11,6 +10,6 @@
 };
 
 static_assert(deref<void*>);
-// sfinae-error@-1{{static assertion failed}}
-// sfinae-note@-2{{because 'void *' does not satisfy 'deref'}}
-// sfinae-note@#FAILED_REQ{{because '*t' would be invalid: ISO C++ does not allow indirection on operand of type 'void *'}}
+// expected-error@-1{{static assertion failed}}
+// expected-note@-2{{because 'void *' does not satisfy 'deref'}}
+// expected-note@#FAILED_REQ{{because '*t' would be invalid: indirection not permitted on operand of type 'void *'}}
diff --git a/clang/test/SemaCXX/reinterpret-cast.cpp b/clang/test/SemaCXX/reinterpret-cast.cpp
--- a/clang/test/SemaCXX/reinterpret-cast.cpp
+++ b/clang/test/SemaCXX/reinterpret-cast.cpp
@@ -214,11 +214,11 @@
   (void)*reinterpret_cast<float*>(v_ptr);
 
   // Casting to void pointer
-  (void)*reinterpret_cast<void*>(&a); // expected-error {{ISO C++ does not allow}}
-  (void)*reinterpret_cast<void*>(&b); // expected-error {{ISO C++ does not allow}}
-  (void)*reinterpret_cast<void*>(&l); // expected-error {{ISO C++ does not allow}}
-  (void)*reinterpret_cast<void*>(&d); // expected-error {{ISO C++ does not allow}}
-  (void)*reinterpret_cast<void*>(&f); // expected-error {{ISO C++ does not allow}}
+  (void)*reinterpret_cast<void*>(&a); // expected-error {{indirection not permitted on operand of type 'void *'}}
+  (void)*reinterpret_cast<void*>(&b); // expected-error {{indirection not permitted on operand of type 'void *'}}
+  (void)*reinterpret_cast<void*>(&l); // expected-error {{indirection not permitted on operand of type 'void *'}}
+  (void)*reinterpret_cast<void*>(&d); // expected-error {{indirection not permitted on operand of type 'void *'}}
+  (void)*reinterpret_cast<void*>(&f); // expected-error {{indirection not permitted on operand of type 'void *'}}
 }
 
 void reinterpret_cast_allowlist () {