diff --git a/src/betterproto/plugin/models.py b/src/betterproto/plugin/models.py
index 93b2aa8cf..f0048c830 100644
--- a/src/betterproto/plugin/models.py
+++ b/src/betterproto/plugin/models.py
@@ -725,6 +725,9 @@ def __post_init__(self) -> None:
         self.parent.methods.append(self)
 
         # Check for imports
+        if "Optional" in self.py_input_message_type:
+            self.output_file.typing_imports.add("Optional")
+
         if "Optional" in self.py_output_message_type:
             self.output_file.typing_imports.add("Optional")
 
diff --git a/tests/inputs/service_complex_structure/payloads/messages.proto b/tests/inputs/service_complex_structure/payloads/messages.proto
new file mode 100644
index 000000000..42c101724
--- /dev/null
+++ b/tests/inputs/service_complex_structure/payloads/messages.proto
@@ -0,0 +1,13 @@
+syntax = "proto3";
+
+import "google/protobuf/duration.proto";
+import "google/protobuf/timestamp.proto";
+
+package service_complex_structure.payloads;
+
+message Test {
+  string name = 1;
+  repeated string comments = 2;
+  google.protobuf.Timestamp when = 3;
+  google.protobuf.Duration duration = 4;
+}
diff --git a/tests/inputs/service_complex_structure/services/service.proto b/tests/inputs/service_complex_structure/services/service.proto
new file mode 100644
index 000000000..d0ea30b3f
--- /dev/null
+++ b/tests/inputs/service_complex_structure/services/service.proto
@@ -0,0 +1,11 @@
+syntax = "proto3";
+
+import "google/protobuf/empty.proto";
+import "payloads/messages.proto";
+
+package service_complex_structure.service;
+
+
+service Test {
+  rpc DoThing (service_complex_structure.payloads.Test) returns (google.protobuf.Empty);
+}
diff --git a/tests/inputs/service_complex_structure/test_service_complex_structure.py b/tests/inputs/service_complex_structure/test_service_complex_structure.py
new file mode 100644
index 000000000..c46428e1b
--- /dev/null
+++ b/tests/inputs/service_complex_structure/test_service_complex_structure.py
@@ -0,0 +1,25 @@
+import pytest
+
+
+def test_payloads_import_is_generated():
+    try:
+        from tests.output_betterproto.service_complex_structure.service import (
+            _payloads__,
+        )
+
+        assert hasattr(_payloads__, "Test")
+    except ImportError:
+        pytest.fail("Required import for type annotations is not generated!")
+
+
+def test_payloads_import_is_generated_pydantic():
+    try:
+        from tests.output_betterproto_pydantic.service_complex_structure.service import (
+            _payloads__,
+        )
+
+        assert hasattr(_payloads__, "Test")
+    except ImportError:
+        pytest.fail(
+            "Required import for type annotations is not generated in pydantic output!"
+        )
diff --git a/tests/util.py b/tests/util.py
index 22c4f9012..78a90a903 100644
--- a/tests/util.py
+++ b/tests/util.py
@@ -34,9 +34,8 @@ def get_files(path, suffix: str) -> Generator[str, None, None]:
             yield os.path.join(r, filename)
 
 
-def get_directories(path):
-    for root, directories, files in os.walk(path):
-        yield from directories
+def get_directories(path: Path) -> Generator[str, None, None]:
+    yield from (entry.name for entry in path.iterdir() if entry.is_dir())
 
 
 async def protoc(
@@ -79,7 +78,7 @@ async def protoc(
             "--custom_opt=pydantic_dataclasses",
             f"--proto_path={path.as_posix()}",
             f"--custom_out={output_dir.as_posix()}",
-            *[p.as_posix() for p in path.glob("*.proto")],
+            *[p.as_posix() for p in path.glob("**/*.proto")],
         ]
     else:
         command = [
@@ -88,7 +87,7 @@ async def protoc(
             "grpc.tools.protoc",
             f"--proto_path={path.as_posix()}",
             f"--{python_out_option}={output_dir.as_posix()}",
-            *[p.as_posix() for p in path.glob("*.proto")],
+            *[p.as_posix() for p in path.glob("**/*.proto")],
         ]
     proc = await asyncio.create_subprocess_exec(
         *command, stdout=asyncio.subprocess.PIPE, stderr=asyncio.subprocess.PIPE