diff --git a/hpb_generator/context.h b/hpb_generator/context.h
index 58aba5e011..d7a7ae9bb0 100644
--- a/hpb_generator/context.h
+++ b/hpb_generator/context.h
@@ -12,6 +12,7 @@
 #include <utility>
 
 #include "absl/strings/ascii.h"
+#include "absl/strings/str_cat.h"
 #include "absl/strings/str_replace.h"
 #include "absl/strings/string_view.h"
 #include "absl/strings/substitute.h"
@@ -102,6 +103,32 @@ inline void EmitFileWarning(const google::protobuf::FileDescriptor* file, Contex
       file->name());
   ctx.Emit("\n");
 }
+
+// TODO: b/346865271 append ::hpb instead of ::protos after namespace swap
+inline std::string NamespaceFromPackageName(absl::string_view package_name) {
+  return absl::StrCat(absl::StrReplaceAll(package_name, {{".", "::"}}),
+                      "::protos");
+}
+
+template <typename T>
+void WrapNamespace(const google::protobuf::FileDescriptor* file, Context& ctx, T&& body) {
+  if (file->package().empty()) {
+    body();
+  } else {
+    ctx.Emit(
+        {
+            {"body", body},
+            {"namespace", NamespaceFromPackageName(file->package())},
+        },
+        R"cc(
+          namespace $namespace$ {
+
+          $body$
+
+          }  // namespace $namespace$
+        )cc");
+  }
+}
 }  // namespace protobuf
 }  // namespace google::hpb_generator
 
diff --git a/hpb_generator/names.cc b/hpb_generator/names.cc
index 8492051ac0..617062ace0 100644
--- a/hpb_generator/names.cc
+++ b/hpb_generator/names.cc
@@ -19,12 +19,6 @@ namespace protobuf = ::proto2;
 
 namespace {
 
-// TODO: b/346865271 append ::hpb instead of ::protos after namespace swap
-std::string NamespaceFromPackageName(absl::string_view package_name) {
-  return absl::StrCat(absl::StrReplaceAll(package_name, {{".", "::"}}),
-                      "::protos");
-}
-
 std::string DotsToColons(const absl::string_view name) {
   return absl::StrReplaceAll(name, {{".", "::"}});
 }
@@ -121,24 +115,6 @@ std::string CppHeaderFilename(const google::protobuf::FileDescriptor* file) {
   return compiler::StripProto(file->name()) + ".upb.proto.h";
 }
 
-void WriteStartNamespace(const protobuf::FileDescriptor* file, Context& ctx) {
-  // Skip namespace generation if package name is not specified.
-  if (file->package().empty()) {
-    return;
-  }
-
-  ctx.EmitLegacy("namespace $0 {\n\n",
-                 NamespaceFromPackageName(file->package()));
-}
-
-void WriteEndNamespace(const protobuf::FileDescriptor* file, Context& ctx) {
-  if (file->package().empty()) {
-    return;
-  }
-  ctx.EmitLegacy("} //  namespace $0\n\n",
-                 NamespaceFromPackageName(file->package()));
-}
-
 std::string CppConstType(const protobuf::FieldDescriptor* field) {
   return CppTypeInternal(field, /* is_const= */ true,
                          /* is_type_parameter= */ false);
diff --git a/hpb_generator/protoc-gen-hpb.cc b/hpb_generator/protoc-gen-hpb.cc
index 0b94b833a5..30d6b4e31e 100644
--- a/hpb_generator/protoc-gen-hpb.cc
+++ b/hpb_generator/protoc-gen-hpb.cc
@@ -163,25 +163,24 @@ void WriteHeader(const protobuf::FileDescriptor* file, Context& ctx,
   }
 
   WriteHeaderMessageForwardDecls(file, ctx, strip_feature_includes);
-  WriteStartNamespace(file, ctx);
 
   std::vector<const protobuf::EnumDescriptor*> this_file_enums =
       SortedEnums(file);
 
-  // Write Class and Enums.
-  WriteEnumDeclarations(this_file_enums, ctx);
-  ctx.Emit("\n");
-
-  for (auto message : this_file_messages) {
-    WriteMessageClassDeclarations(message, this_file_exts, this_file_enums,
-                                  ctx);
-  }
-  ctx.Emit("\n");
+  WrapNamespace(file, ctx, [&]() {
+    // Write Class and Enums.
+    WriteEnumDeclarations(this_file_enums, ctx);
+    ctx.Emit("\n");
 
-  WriteExtensionIdentifiersHeader(this_file_exts, ctx);
-  ctx.Emit("\n");
+    for (auto message : this_file_messages) {
+      WriteMessageClassDeclarations(message, this_file_exts, this_file_enums,
+                                    ctx);
+    }
+    ctx.Emit("\n");
 
-  WriteEndNamespace(file, ctx);
+    WriteExtensionIdentifiersHeader(this_file_exts, ctx);
+    ctx.Emit("\n");
+  });
 
   ctx.Emit("\n#include \"upb/port/undef.inc\"\n\n");
   // End of "C" section.
@@ -213,12 +212,12 @@ void WriteSource(const protobuf::FileDescriptor* file, Context& ctx,
   }
   ctx.EmitLegacy("#include \"upb/port/def.inc\"\n");
 
-  WriteStartNamespace(file, ctx);
-  WriteMessageImplementations(file, ctx);
-  const std::vector<const protobuf::FieldDescriptor*> this_file_exts =
-      SortedExtensions(file);
-  WriteExtensionIdentifiers(this_file_exts, ctx);
-  WriteEndNamespace(file, ctx);
+  WrapNamespace(file, ctx, [&]() {
+    WriteMessageImplementations(file, ctx);
+    const std::vector<const protobuf::FieldDescriptor*> this_file_exts =
+        SortedExtensions(file);
+    WriteExtensionIdentifiers(this_file_exts, ctx);
+  });
 
   ctx.Emit("#include \"upb/port/undef.inc\"\n\n");
 }
@@ -238,23 +237,21 @@ void WriteTypedefForwardingHeader(
     const protobuf::FileDescriptor* file,
     const std::vector<const protobuf::Descriptor*>& file_messages,
     Context& ctx) {
-  WriteStartNamespace(file, ctx);
-
-  // Forward-declare types defined in this file.
-  for (auto message : file_messages) {
-    ctx.EmitLegacy(
-        R"cc(
-          class $0;
-          namespace internal {
-          class $0Access;
-          class $0Proxy;
-          class $0CProxy;
-          }  // namespace internal
-        )cc",
-        ClassName(message));
-  }
+  WrapNamespace(file, ctx, [&]() {
+    // Forward-declare types defined in this file.
+    for (auto message : file_messages) {
+      ctx.Emit({{"class_name", ClassName(message)}},
+               R"cc(
+                 class $class_name$;
+                 namespace internal {
+                 class $class_name$Access;
+                 class $class_name$Proxy;
+                 class $class_name$CProxy;
+                 }  // namespace internal
+               )cc");
+    }
+  });
   ctx.Emit("\n");
-  WriteEndNamespace(file, ctx);
 }
 
 /// Writes includes for upb C minitables and fwd.h for transitive typedefs.