diff --git a/src/raspberrypi/rascsi_response.cpp b/src/raspberrypi/rascsi_response.cpp
index d203e8ed..fa6a3d6c 100644
--- a/src/raspberrypi/rascsi_response.cpp
+++ b/src/raspberrypi/rascsi_response.cpp
@@ -394,7 +394,10 @@ PbOperationInfo *RascsiResponse::GetOperationInfo(PbResult& result)
 	AddOperationParameter(*parameters, "ids", "Comma-separated device ID list");
 
 	parameters = AddOperation(*operation_info, SHUT_DOWN, "Shut down or reboot");
-	AddOperationParameter(*parameters, "mode", "Shutdown mode");
+	PbOperationParameter *parameter = AddOperationParameter(*parameters, "mode", "Shutdown mode");
+	parameter->add_values("rascsi");
+	parameter->add_values("system");
+	parameter->add_values("reboot");
 
 	parameters = AddOperation(*operation_info, CREATE_IMAGE, "Create an image file");
 	AddOperationParameter(*parameters, "file", "Image file name");
@@ -439,12 +442,14 @@ PbOperationParameters *RascsiResponse::AddOperation(PbOperationInfo& operation_i
 	return parameters;
 }
 
-void RascsiResponse::AddOperationParameter(PbOperationParameters& parameters, const string& name, const string& description,
-		const string& type, bool is_mandatory)
+PbOperationParameter *RascsiResponse::AddOperationParameter(PbOperationParameters& parameters, const string& name,
+		const string& description, const string& type, bool is_mandatory)
 {
 	PbOperationParameter *parameter = parameters.add_parameters();
 	parameter->set_name(name);
 	(*parameter->mutable_description())["en"] = description;
 	parameter->set_type(type);
 	parameter->set_is_mandatory(is_mandatory);
+
+	return parameter;
 }
diff --git a/src/raspberrypi/rascsi_response.h b/src/raspberrypi/rascsi_response.h
index c9c8be89..5ca379ad 100644
--- a/src/raspberrypi/rascsi_response.h
+++ b/src/raspberrypi/rascsi_response.h
@@ -54,5 +54,5 @@ private:
 	void GetDeviceTypeProperties(PbDeviceTypesInfo&, PbDeviceType);
 	void GetAvailableImages(PbResult& result, PbServerInfo&);
 	PbOperationParameters *AddOperation(PbOperationInfo&, const PbOperation&, const string&);
-	void AddOperationParameter(PbOperationParameters&, const string&, const string&, const string& = "string", bool = true);
+	PbOperationParameter *AddOperationParameter(PbOperationParameters&, const string&, const string&, const string& = "string", bool = true);
 };
diff --git a/src/raspberrypi/rasctl_display.cpp b/src/raspberrypi/rasctl_display.cpp
index 8d36f4c6..3e7f5c1c 100644
--- a/src/raspberrypi/rasctl_display.cpp
+++ b/src/raspberrypi/rasctl_display.cpp
@@ -295,6 +295,19 @@ void RasctlDisplay::DisplayOperationInfo(const PbOperationInfo& operation_info)
 				cout << " (" << parameter.description().at("en") << ")";
 			}
 			cout << endl;
+
+			if (parameter.values_size()) {
+				cout << "      Permitted values: ";
+				bool isFirst = true;
+				for (const auto& value : parameter.values()) {
+					if (!isFirst) {
+						cout << ", ";
+					}
+					isFirst = false;
+					cout << value;
+				}
+				cout << endl;
+			}
 		}
 	}
 }