diff --git a/robotpy_build/autowrap/cxxparser.py b/robotpy_build/autowrap/cxxparser.py
index d2d77c82..24384505 100644
--- a/robotpy_build/autowrap/cxxparser.py
+++ b/robotpy_build/autowrap/cxxparser.py
@@ -1637,7 +1637,7 @@ def _on_fn_make_lambda(self, data: FunctionData, fctx: FunctionContext):
             for out in reversed(tmp_params):
                 odef = out.default
                 if not odef:
-                    lambda_pre.insert(0, f"{out.cpp_type} {out.arg_name}")
+                    lambda_pre.insert(0, f"{out.cpp_type} {out.arg_name}{{}}")
                 elif odef.startswith("{"):
                     lambda_pre.insert(0, f"{out.cpp_type} {out.arg_name}{odef}")
                 else:
diff --git a/tests/cpp/rpytest/ft/__init__.py b/tests/cpp/rpytest/ft/__init__.py
index 9e919f01..a1c25b0d 100644
--- a/tests/cpp/rpytest/ft/__init__.py
+++ b/tests/cpp/rpytest/ft/__init__.py
@@ -108,6 +108,7 @@
     fnParamFundConstRef,
     fnParamFundPtr,
     fnParamFundRef,
+    fnParamOutNotSet,
     fnRenamed,
     fnRenamedParam,
     fnSimpleDefaultParam,
@@ -225,6 +226,7 @@
     "fnParamFundConstRef",
     "fnParamFundPtr",
     "fnParamFundRef",
+    "fnParamOutNotSet",
     "fnRenamed",
     "fnRenamedParam",
     "fnSimpleDefaultParam",
diff --git a/tests/cpp/rpytest/ft/include/parameters.h b/tests/cpp/rpytest/ft/include/parameters.h
index cc00dc78..68f2ab94 100644
--- a/tests/cpp/rpytest/ft/include/parameters.h
+++ b/tests/cpp/rpytest/ft/include/parameters.h
@@ -28,6 +28,11 @@ int fnParamFundPtr(int x, int * y)
     return x - 1;
 }
 
+// parameters that are not set should be zero initialized
+int fnParamOutNotSet(int *z) {
+    return 1;
+}
+
 // do a namespace thing because we messed that up once
 namespace ohno {
     // parameters that are pointers and fundamental types are out by default
diff --git a/tests/test_ft_parameters.py b/tests/test_ft_parameters.py
index 602edbf9..aca76534 100644
--- a/tests/test_ft_parameters.py
+++ b/tests/test_ft_parameters.py
@@ -22,6 +22,10 @@ def test_fund_const_ref():
     assert ft.fnParamFundConstRef(1, 2) == 3
 
 
+def test_param_out_not_set():
+    assert ft.fnParamOutNotSet() == (1, 0)
+
+
 def test_fn_disable_none():
     with pytest.raises(TypeError):
         ft.fnParamDisableNone(None)