diff --git a/src/modules/meson.build b/src/modules/meson.build
index ef1d986e9..98bc38642 100644
--- a/src/modules/meson.build
+++ b/src/modules/meson.build
@@ -80,7 +80,11 @@ test('pw-test-protocol-native',
 			c_args : libpipewire_c_args,
 			include_directories : [configinc, spa_inc ],
 			dependencies : [pipewire_dep],
-			install : false))
+			install : false),
+	env : [
+		'SPA_PLUGIN_DIR=@0@/spa/plugins/'.format(meson.build_root()),
+		'PIPEWIRE_MODULE_DIR=@0@/src/modules/'.format(meson.build_root())
+	])
 
 pipewire_module_audio_dsp = shared_library('pipewire-module-audio-dsp',
   [ 'module-audio-dsp.c',
diff --git a/src/modules/module-protocol-native/test-connection.c b/src/modules/module-protocol-native/test-connection.c
index f3f687d88..2f76d69a7 100644
--- a/src/modules/module-protocol-native/test-connection.c
+++ b/src/modules/module-protocol-native/test-connection.c
@@ -109,6 +109,13 @@ static void test_read_write(struct pw_protocol_native_connection *in,
 	spa_assert(read_message(in) == 0);
 	spa_assert(read_message(in) == 0);
 	spa_assert(read_message(in) == -1);
+
+	write_message(out, 1);
+	write_message(out, 2);
+	pw_protocol_native_connection_flush(out);
+	spa_assert(read_message(in) == 0);
+	spa_assert(read_message(in) == 0);
+	spa_assert(read_message(in) == -1);
 }
 
 int main(int argc, char *argv[])