diff --git a/src/modules/action.hh b/src/modules/action.hh
index a22b709..51f298b 100644
--- a/src/modules/action.hh
+++ b/src/modules/action.hh
@@ -1,5 +1,4 @@
-#ifndef ACTION_HH
-#define ACTION_HH
+#pragma once
 #include <string>
 
 struct Action {
@@ -9,5 +8,3 @@ struct Action {
     Action(std::string name, bool has_target);
     bool operator==(const Action &other) const;
 };
-
-#endif  // !ACTION_HH
diff --git a/src/modules/event.hh b/src/modules/event.hh
index 5997743..98f7ba8 100644
--- a/src/modules/event.hh
+++ b/src/modules/event.hh
@@ -1,5 +1,4 @@
-#ifndef EVENT_HH
-#define EVENT_HH
+#pragma once
 
 #include "./action.hh"
 
@@ -42,5 +41,3 @@ struct Event {
           std::initializer_list<Action> prohibits,
           std::initializer_list<Action> allows);
 };
-
-#endif  // !EVENT_HH
diff --git a/src/modules/player.hh b/src/modules/player.hh
index 8f0b25c..98abb51 100644
--- a/src/modules/player.hh
+++ b/src/modules/player.hh
@@ -1,6 +1,4 @@
-#ifndef PLAYER_HH
-#define PLAYER_HH
-
+#pragma once
 #include "./role.hh"
 
 #include <cstdint>
@@ -24,5 +22,3 @@ struct Player {
     Player(uint32_t id, std::string username, Role role, player::Status status);
     bool operator==(const Player &other) const;
 };
-
-#endif  // !PLAYER_HH
diff --git a/src/modules/role.hh b/src/modules/role.hh
index e2e19da..4483c40 100644
--- a/src/modules/role.hh
+++ b/src/modules/role.hh
@@ -1,5 +1,4 @@
-#ifndef ROLE_HH
-#define ROLE_HH
+#pragma once
 
 #include "./action.hh"
 
@@ -11,5 +10,3 @@ struct Role {
     explicit Role(std::vector<Action> actions);
     Role(std::initializer_list<Action> actions);
 };
-
-#endif  // !ROLE_HH
diff --git a/src/modules/room.hh b/src/modules/room.hh
index ff0e98c..4592267 100644
--- a/src/modules/room.hh
+++ b/src/modules/room.hh
@@ -1,5 +1,4 @@
-#ifndef ROOM_HH
-#define ROOM_HH
+#pragma once
 
 #include "./player.hh"
 
@@ -29,5 +28,3 @@ struct Room {
     Room(
       uint32_t id, std::string title, uint32_t created_at, room::Status status, std::initializer_list<Player> players);
 };
-
-#endif  // !ROOM_HH
diff --git a/src/modules/time.hh b/src/modules/time.hh
index 3a746e5..73f0fa8 100644
--- a/src/modules/time.hh
+++ b/src/modules/time.hh
@@ -1,9 +1,6 @@
-#ifndef TIME_HH
-#define TIME_HH
+#pragma once
 
 #include <cstdint>
 #include <ctime>
 
 std::tm *create_utc_timestamp(uint32_t timestamp);
-
-#endif  // !TIME_HH
diff --git a/src/validation.hh b/src/validation.hh
index 9033f27..9b183c5 100644
--- a/src/validation.hh
+++ b/src/validation.hh
@@ -1,6 +1,4 @@
-#ifndef VALIDATION_HH
-#define VALIDATION_HH
-
+#pragma once
 #include "modules/event.hh"
 #include "modules/player.hh"
 #include "modules/room.hh"
@@ -24,5 +22,3 @@ namespace validation {
 }  // namespace validation
 
 int validate_action(Player *actor, const Action *action, Room *room, std::vector<Event> *relatedEvents, Player *target);
-
-#endif  // !VALIDATION_HH