diff --git a/src/google/protobuf/compiler/cpp/generator.cc b/src/google/protobuf/compiler/cpp/generator.cc
index 4284cec120e74..24e48e55e7336 100644
--- a/src/google/protobuf/compiler/cpp/generator.cc
+++ b/src/google/protobuf/compiler/cpp/generator.cc
@@ -67,6 +67,9 @@ absl::flat_hash_map<absl::string_view, std::string> CommonVars(
       {"hrule_thick", kThickSeparator},
       {"hrule_thin", kThinSeparator},
 
+      {"nullable", "PROTOBUF_NULLABLE"},
+      {"nonnull", "PROTOBUF_NONNULL"},
+
       // Warning: there is some clever naming/splitting here to avoid extract
       // script rewrites.  The names of these variables must not be things that
       // the extract script will rewrite.  That's why we use "CHK" (for example)
diff --git a/src/google/protobuf/port_def.inc b/src/google/protobuf/port_def.inc
index 8225445450dc8..30c2e396ef14c 100644
--- a/src/google/protobuf/port_def.inc
+++ b/src/google/protobuf/port_def.inc
@@ -902,6 +902,14 @@ namespace internal {
 #define PROTOBUF_DEPRECATE_AND_INLINE() [[deprecated]]
 #endif
 
+#ifdef PROTOBUF_NONNULL
+#error PROTOBUF_NONNULL was previously defined
+#endif
+#ifndef PROTOBUF_NONNULL
+#define PROTOBUF_NONNULL
+#define PROTOBUF_NULLABLE
+#endif
+
 namespace google {
 namespace protobuf {
 namespace internal {
diff --git a/src/google/protobuf/port_undef.inc b/src/google/protobuf/port_undef.inc
index 0fb70db0a97c8..60a96fce1de83 100644
--- a/src/google/protobuf/port_undef.inc
+++ b/src/google/protobuf/port_undef.inc
@@ -63,6 +63,8 @@
 #undef PROTOBUF_TC_PARAM_DECL
 #undef PROTOBUF_DEBUG
 #undef PROTOBUF_NO_THREADLOCAL
+#undef PROTOBUF_NONNULL
+#undef PROTOBUF_NULLABLE
 
 #ifdef PROTOBUF_FUTURE_BREAKING_CHANGES
 #undef PROTOBUF_FUTURE_BREAKING_CHANGES