diff --git a/libs/elevator/include/elevator/elevator_state.hpp b/libs/elevator/include/elevator/elevator_state.hpp
index d3ac8f3..862dfef 100644
--- a/libs/elevator/include/elevator/elevator_state.hpp
+++ b/libs/elevator/include/elevator/elevator_state.hpp
@@ -24,7 +24,7 @@ class ElevatorState {
     uint64_t Version() const;
     common::BoolTable Requests() const;
     common::Inertia Inertia() const;
-    bool Valid() const;
+    [[nodiscard]] bool Valid() const;
 
     // Setters
     void SetId(int id);
@@ -45,7 +45,7 @@ class ElevatorState {
     void OnUpdate(const ElevatorState& state);
     void IncrementVersion() { version_++; }
     void OnWatchdogTimeout();
-    bool Usable() const;
+    [[nodiscard]] bool Usable() const;
 
 private:
     int id_{-1};
diff --git a/libs/network/include/network/udp_bcast.hpp b/libs/network/include/network/udp_bcast.hpp
index 5078f98..af2464c 100644
--- a/libs/network/include/network/udp_bcast.hpp
+++ b/libs/network/include/network/udp_bcast.hpp
@@ -18,7 +18,7 @@ class NetworkPacket {
               elev::ordersync::CabOrderTable* cab_button_orders);
 
     int Id() const { return id_; }
-    bool Valid() const;
+    [[nodiscard]] bool Valid() const;
     elev::ordersync::OrderTable* Orders() { return &orders_; }
     const elev::ordersync::OrderTable* Orders() const { return &orders_; }
     elev::elevator::ElevatorState* State() { return &state_; }
@@ -39,7 +39,7 @@ class UdpBroadcaster {
     UdpBroadcaster(uint16_t port, const std::string& bcast_ip);
     ~UdpBroadcaster();
 
-    bool SendPacket(NetworkPacket* packet);
+    [[nodiscard]] bool SendPacket(NetworkPacket* packet);
 
 private:
     int socket_fd_{-1};
@@ -52,7 +52,7 @@ class UdpReciever {
     ~UdpReciever();
 
     void Close();
-    bool RecievePacket(NetworkPacket* packet);
+    [[nodiscard]] bool RecievePacket(NetworkPacket* packet);
 
 private:
     int socket_fd_{-1};
diff --git a/libs/ordersync/include/ordersync/ordersync.hpp b/libs/ordersync/include/ordersync/ordersync.hpp
index 658d4c4..fb269dd 100644
--- a/libs/ordersync/include/ordersync/ordersync.hpp
+++ b/libs/ordersync/include/ordersync/ordersync.hpp
@@ -23,8 +23,8 @@ class Order {
     OrderStatus Status() const { return status_; }
     int AssignedId() const { return assigned_id_; }
     uint32_t ObservedMask() const { return observed_mask_; }
-    bool ObservedBy(int elev_id) const;
-    bool Valid() const;
+    [[nodiscard]] bool ObservedBy(int elev_id) const;
+    [[nodiscard]] bool Valid() const;
 
     // State machine
     void OnUpdate(const Order& rcv);
@@ -55,7 +55,7 @@ class OrderTable {
     ordersync::Order* Order(int floor, int btn);
     const ordersync::Order* Order(int floor, int btn) const;
     BoolTable ToBoolTable(int elev_id) const;
-    bool Valid() const;
+    [[nodiscard]] bool Valid() const;
 
 private:
     std::array<std::array<ordersync::Order, kButtons>, kFloors> table_{};