diff --git a/pw_build/python.gni b/pw_build/python.gni
index 5bb412c..b94a526 100644
--- a/pw_build/python.gni
+++ b/pw_build/python.gni
@@ -243,7 +243,7 @@
 
   if (_should_lint || _test_sources != []) {
     # Packages that must be installed to use the package or run its tests.
-    _test_install_deps = []
+    _test_install_deps = [ ":$_internal_target.install" ]
     foreach(dep, _python_test_deps) {
       _test_install_deps += [ "$dep.install" ]
     }
diff --git a/pw_protobuf_compiler/BUILD.gn b/pw_protobuf_compiler/BUILD.gn
index 0d678a0..f34438f 100644
--- a/pw_protobuf_compiler/BUILD.gn
+++ b/pw_protobuf_compiler/BUILD.gn
@@ -46,5 +46,6 @@
 
 # PyPI Requirements needed to install Python protobuf packages.
 pw_python_requirements("protobuf_requirements") {
-  requirements = [ "mypy-protobuf" ]
+  # mypy-protobuf 1.24 is required to support optional fields in proto3.
+  requirements = [ "mypy-protobuf>=1.24" ]
 }
diff --git a/pw_protobuf_compiler/py/pw_protobuf_compiler/generate_protos.py b/pw_protobuf_compiler/py/pw_protobuf_compiler/generate_protos.py
index 7bfd76b..3d2932b 100644
--- a/pw_protobuf_compiler/py/pw_protobuf_compiler/generate_protos.py
+++ b/pw_protobuf_compiler/py/pw_protobuf_compiler/generate_protos.py
@@ -21,7 +21,7 @@
 import sys
 import tempfile
 
-from typing import Callable, Dict, List, Optional
+from typing import Callable, Dict, Optional, Tuple
 
 # Make sure dependencies are optional, since this script may be run when
 # installing Python package dependencies through GN.
@@ -32,6 +32,8 @@
 
 _LOG = logging.getLogger(__name__)
 
+_COMMON_FLAGS = ('--experimental_allow_proto3_optional', )
+
 
 def argument_parser(
     parser: Optional[argparse.ArgumentParser] = None
@@ -69,56 +71,66 @@
     return parser
 
 
-def protoc_cc_args(args: argparse.Namespace) -> List[str]:
-    return [
+def protoc_cc_args(args: argparse.Namespace) -> Tuple[str, ...]:
+    return _COMMON_FLAGS + (
         '--plugin',
         f'protoc-gen-custom={args.plugin_path}',
         '--custom_out',
         args.out_dir,
-    ]
+    )
 
 
-def protoc_go_args(args: argparse.Namespace) -> List[str]:
-    return ['--go_out', f'plugins=grpc:{args.out_dir}']
+def protoc_go_args(args: argparse.Namespace) -> Tuple[str, ...]:
+    return _COMMON_FLAGS + (
+        '--go_out',
+        f'plugins=grpc:{args.out_dir}',
+    )
 
 
-def protoc_nanopb_args(args: argparse.Namespace) -> List[str]:
+def protoc_nanopb_args(args: argparse.Namespace) -> Tuple[str, ...]:
     # nanopb needs to know of the include path to parse *.options files
-    return [
+    return _COMMON_FLAGS + (
         '--plugin',
         f'protoc-gen-nanopb={args.plugin_path}',
         # nanopb_opt provides the flags to use for nanopb_out. Windows doesn't
         # like when you merge the two using the `flag,...:out` syntax.
         f'--nanopb_opt=-I{args.module_path}',
         f'--nanopb_out={args.out_dir}',
-    ]
+    )
 
 
-def protoc_nanopb_rpc_args(args: argparse.Namespace) -> List[str]:
-    return [
+def protoc_nanopb_rpc_args(args: argparse.Namespace) -> Tuple[str, ...]:
+    return _COMMON_FLAGS + (
         '--plugin',
         f'protoc-gen-custom={args.plugin_path}',
         '--custom_out',
         args.out_dir,
-    ]
+    )
 
 
-def protoc_raw_rpc_args(args: argparse.Namespace) -> List[str]:
-    return [
+def protoc_raw_rpc_args(args: argparse.Namespace) -> Tuple[str, ...]:
+    return _COMMON_FLAGS + (
         '--plugin',
         f'protoc-gen-custom={args.plugin_path}',
         '--custom_out',
         args.out_dir,
-    ]
+    )
 
 
-def protoc_python_args(args: argparse.Namespace) -> List[str]:
-    return ['--python_out', args.out_dir, '--mypy_out', args.out_dir]
+def protoc_python_args(args: argparse.Namespace) -> Tuple[str, ...]:
+    return _COMMON_FLAGS + (
+        '--python_out',
+        args.out_dir,
+        '--mypy_out',
+        args.out_dir,
+    )
 
 
+_DefaultArgsFunction = Callable[[argparse.Namespace], Tuple[str, ...]]
+
 # Default additional protoc arguments for each supported language.
 # TODO(frolv): Make these overridable with a command-line argument.
-DEFAULT_PROTOC_ARGS: Dict[str, Callable[[argparse.Namespace], List[str]]] = {
+DEFAULT_PROTOC_ARGS: Dict[str, _DefaultArgsFunction] = {
     'pwpb': protoc_cc_args,
     'go': protoc_go_args,
     'nanopb': protoc_nanopb_args,
diff --git a/pw_rpc/py/pw_rpc/plugin.py b/pw_rpc/py/pw_rpc/plugin.py
index 595b436..44337d9 100644
--- a/pw_rpc/py/pw_rpc/plugin.py
+++ b/pw_rpc/py/pw_rpc/plugin.py
@@ -63,5 +63,11 @@
     request = plugin_pb2.CodeGeneratorRequest.FromString(data)
     response = plugin_pb2.CodeGeneratorResponse()
     process_proto_request(codegen, request, response)
+
+    # Declare that this plugin supports optional fields in proto3. No proto
+    # message code is generated, so optional in proto3 is supported trivially.
+    response.supported_features |= (  # type: ignore[attr-defined]
+        response.FEATURE_PROTO3_OPTIONAL)  # type: ignore[attr-defined]
+
     sys.stdout.buffer.write(response.SerializeToString())
     return 0