diff --git a/apps/openmw/mwinput/inputmanagerimp.hpp b/apps/openmw/mwinput/inputmanagerimp.hpp
index d4693ff28..4eaee9b69 100644
--- a/apps/openmw/mwinput/inputmanagerimp.hpp
+++ b/apps/openmw/mwinput/inputmanagerimp.hpp
@@ -1,5 +1,5 @@
-#ifndef _MWINPUT_MWINPUTMANAGERIMP_H
-#define _MWINPUT_MWINPUTMANAGERIMP_H
+#ifndef MWINPUT_MWINPUTMANAGERIMP_H
+#define MWINPUT_MWINPUTMANAGERIMP_H
 
 #include "../mwgui/mode.hpp"
 
diff --git a/apps/openmw/mwrender/activatoranimation.hpp b/apps/openmw/mwrender/activatoranimation.hpp
index f3ea38f44..eb3e5815e 100644
--- a/apps/openmw/mwrender/activatoranimation.hpp
+++ b/apps/openmw/mwrender/activatoranimation.hpp
@@ -1,5 +1,5 @@
-#ifndef _GAME_RENDER_ACTIVATORANIMATION_H
-#define _GAME_RENDER_ACTIVATORANIMATION_H
+#ifndef GAME_RENDER_ACTIVATORANIMATION_H
+#define GAME_RENDER_ACTIVATORANIMATION_H
 
 #include "animation.hpp"
 
diff --git a/apps/openmw/mwrender/actors.hpp b/apps/openmw/mwrender/actors.hpp
index d91321843..af71525fa 100644
--- a/apps/openmw/mwrender/actors.hpp
+++ b/apps/openmw/mwrender/actors.hpp
@@ -1,5 +1,5 @@
-#ifndef _GAME_RENDER_ACTORS_H
-#define _GAME_RENDER_ACTORS_H
+#ifndef GAME_RENDER_ACTORS_H
+#define GAME_RENDER_ACTORS_H
 
 #include <openengine/ogre/renderer.hpp>
 
diff --git a/apps/openmw/mwrender/animation.hpp b/apps/openmw/mwrender/animation.hpp
index 72d1c100e..573f769c3 100644
--- a/apps/openmw/mwrender/animation.hpp
+++ b/apps/openmw/mwrender/animation.hpp
@@ -1,5 +1,5 @@
-#ifndef _GAME_RENDER_ANIMATION_H
-#define _GAME_RENDER_ANIMATION_H
+#ifndef GAME_RENDER_ANIMATION_H
+#define GAME_RENDER_ANIMATION_H
 
 #include <OgreController.h>
 #include <OgreVector3.h>
diff --git a/apps/openmw/mwrender/creatureanimation.hpp b/apps/openmw/mwrender/creatureanimation.hpp
index 0c277d198..a902df5d8 100644
--- a/apps/openmw/mwrender/creatureanimation.hpp
+++ b/apps/openmw/mwrender/creatureanimation.hpp
@@ -1,5 +1,5 @@
-#ifndef _GAME_RENDER_CREATUREANIMATION_H
-#define _GAME_RENDER_CREATUREANIMATION_H
+#ifndef GAME_RENDER_CREATUREANIMATION_H
+#define GAME_RENDER_CREATUREANIMATION_H
 
 #include "animation.hpp"
 
diff --git a/apps/openmw/mwrender/debugging.hpp b/apps/openmw/mwrender/debugging.hpp
index 4a574017c..39be34cb0 100644
--- a/apps/openmw/mwrender/debugging.hpp
+++ b/apps/openmw/mwrender/debugging.hpp
@@ -1,5 +1,5 @@
-#ifndef _GAME_RENDER_MWSCENE_H
-#define _GAME_RENDER_MWSCENE_H
+#ifndef GAME_RENDER_MWSCENE_H
+#define GAME_RENDER_MWSCENE_H
 
 #include <utility>
 #include <openengine/ogre/renderer.hpp>
diff --git a/apps/openmw/mwrender/globalmap.hpp b/apps/openmw/mwrender/globalmap.hpp
index dd3787b62..aad9adcc4 100644
--- a/apps/openmw/mwrender/globalmap.hpp
+++ b/apps/openmw/mwrender/globalmap.hpp
@@ -1,5 +1,5 @@
-#ifndef _GAME_RENDER_GLOBALMAP_H
-#define _GAME_RENDER_GLOBALMAP_H
+#ifndef GAME_RENDER_GLOBALMAP_H
+#define GAME_RENDER_GLOBALMAP_H
 
 #include <string>
 
diff --git a/apps/openmw/mwrender/localmap.hpp b/apps/openmw/mwrender/localmap.hpp
index 538489640..638469d2d 100644
--- a/apps/openmw/mwrender/localmap.hpp
+++ b/apps/openmw/mwrender/localmap.hpp
@@ -1,5 +1,5 @@
-#ifndef _GAME_RENDER_LOCALMAP_H
-#define _GAME_RENDER_LOCALMAP_H
+#ifndef GAME_RENDER_LOCALMAP_H
+#define GAME_RENDER_LOCALMAP_H
 
 #include <openengine/ogre/renderer.hpp>
 
diff --git a/apps/openmw/mwrender/npcanimation.hpp b/apps/openmw/mwrender/npcanimation.hpp
index 8edcc04be..6f0403b9d 100644
--- a/apps/openmw/mwrender/npcanimation.hpp
+++ b/apps/openmw/mwrender/npcanimation.hpp
@@ -1,5 +1,5 @@
-#ifndef _GAME_RENDER_NPCANIMATION_H
-#define _GAME_RENDER_NPCANIMATION_H
+#ifndef GAME_RENDER_NPCANIMATION_H
+#define GAME_RENDER_NPCANIMATION_H
 
 #include "animation.hpp"
 
diff --git a/apps/openmw/mwrender/objects.hpp b/apps/openmw/mwrender/objects.hpp
index 8a5074503..665a1e657 100644
--- a/apps/openmw/mwrender/objects.hpp
+++ b/apps/openmw/mwrender/objects.hpp
@@ -1,5 +1,5 @@
-#ifndef _GAME_RENDER_OBJECTS_H
-#define _GAME_RENDER_OBJECTS_H
+#ifndef GAME_RENDER_OBJECTS_H
+#define GAME_RENDER_OBJECTS_H
 
 #include <OgreColourValue.h>
 #include <OgreAxisAlignedBox.h>
diff --git a/apps/openmw/mwrender/occlusionquery.hpp b/apps/openmw/mwrender/occlusionquery.hpp
index 983361c18..6974f37b9 100644
--- a/apps/openmw/mwrender/occlusionquery.hpp
+++ b/apps/openmw/mwrender/occlusionquery.hpp
@@ -1,5 +1,5 @@
-#ifndef _GAME_OCCLUSION_QUERY_H
-#define _GAME_OCCLUSION_QUERY_H
+#ifndef GAME_OCCLUSION_QUERY_H
+#define GAME_OCCLUSION_QUERY_H
 
 #include <OgreRenderObjectListener.h>
 #include <OgreRenderQueueListener.h>
diff --git a/apps/openmw/mwrender/renderinginterface.hpp b/apps/openmw/mwrender/renderinginterface.hpp
index 8ae2c0f8f..02f3c804a 100644
--- a/apps/openmw/mwrender/renderinginterface.hpp
+++ b/apps/openmw/mwrender/renderinginterface.hpp
@@ -1,5 +1,5 @@
-#ifndef _GAME_RENDERING_INTERFACE_H
-#define _GAME_RENDERING_INTERFACE_H
+#ifndef GAME_RENDERING_INTERFACE_H
+#define GAME_RENDERING_INTERFACE_H
 
 namespace MWRender
 {
diff --git a/apps/openmw/mwrender/renderingmanager.hpp b/apps/openmw/mwrender/renderingmanager.hpp
index b13e546e8..37488b157 100644
--- a/apps/openmw/mwrender/renderingmanager.hpp
+++ b/apps/openmw/mwrender/renderingmanager.hpp
@@ -1,5 +1,5 @@
-#ifndef _GAME_RENDERING_MANAGER_H
-#define _GAME_RENDERING_MANAGER_H
+#ifndef GAME_RENDERING_MANAGER_H
+#define GAME_RENDERING_MANAGER_H
 
 #include "sky.hpp"
 #include "debugging.hpp"
diff --git a/components/settings/settings.hpp b/components/settings/settings.hpp
index e9858eb94..b7c7d59a9 100644
--- a/components/settings/settings.hpp
+++ b/components/settings/settings.hpp
@@ -1,5 +1,5 @@
-#ifndef _COMPONENTS_SETTINGS_H
-#define _COMPONENTS_SETTINGS_H
+#ifndef COMPONENTS_SETTINGS_H
+#define COMPONENTS_SETTINGS_H
 
 #include <OgreConfigFile.h>
 
diff --git a/extern/oics/ICSChannel.h b/extern/oics/ICSChannel.h
index f98f0d94d..5ec6cd575 100644
--- a/extern/oics/ICSChannel.h
+++ b/extern/oics/ICSChannel.h
@@ -24,8 +24,8 @@ OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 ------------------------------------------------------- */
 
-#ifndef _Channel_H_
-#define _Channel_H_
+#ifndef OICS_Channel_H_
+#define OICS_Channel_H_
 
 #include "ICSPrerequisites.h"
 
@@ -119,4 +119,4 @@ namespace ICS
 }
 
 
-#endif
\ No newline at end of file
+#endif
diff --git a/extern/oics/ICSControl.h b/extern/oics/ICSControl.h
index 7939c86b9..ebf75a3fe 100644
--- a/extern/oics/ICSControl.h
+++ b/extern/oics/ICSControl.h
@@ -24,8 +24,8 @@ OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 ------------------------------------------------------- */
 
-#ifndef _Control_H_
-#define _Control_H_
+#ifndef OICS_Control_H_
+#define OICS_Control_H_
 
 #include "ICSPrerequisites.h"
 
diff --git a/extern/oics/ICSInputControlSystem.h b/extern/oics/ICSInputControlSystem.h
index f42f9c0b5..907cba5fc 100644
--- a/extern/oics/ICSInputControlSystem.h
+++ b/extern/oics/ICSInputControlSystem.h
@@ -24,8 +24,8 @@ OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 ------------------------------------------------------- */
 
-#ifndef _InputControlSystem_H_
-#define _InputControlSystem_H_
+#ifndef OICS_InputControlSystem_H_
+#define OICS_InputControlSystem_H_
 
 #include "ICSPrerequisites.h"
 
diff --git a/extern/sdl4ogre/OISCompat.h b/extern/sdl4ogre/OISCompat.h
index 3cffa143d..a0acc5837 100644
--- a/extern/sdl4ogre/OISCompat.h
+++ b/extern/sdl4ogre/OISCompat.h
@@ -1,5 +1,5 @@
-#ifndef _OIS_SDL_COMPAT_H
-#define _OIS_SDL_COMPAT_H
+#ifndef OIS_SDL_COMPAT_H
+#define OIS_SDL_COMPAT_H
 
 #include <SDL_events.h>
 #include <SDL_types.h>
diff --git a/extern/sdl4ogre/cursormanager.hpp b/extern/sdl4ogre/cursormanager.hpp
index 35ec92a70..3036b236b 100644
--- a/extern/sdl4ogre/cursormanager.hpp
+++ b/extern/sdl4ogre/cursormanager.hpp
@@ -1,5 +1,5 @@
-#ifndef _SDL4OGRE_CURSOR_MANAGER_H
-#define _SDL4OGRE_CURSOR_MANAGER_H
+#ifndef SDL4OGRE_CURSOR_MANAGER_H
+#define SDL4OGRE_CURSOR_MANAGER_H
 
 #include <SDL_types.h>
 #include <string>
diff --git a/extern/sdl4ogre/sdlcursormanager.hpp b/extern/sdl4ogre/sdlcursormanager.hpp
index 7ba69f013..7e3e59b4a 100644
--- a/extern/sdl4ogre/sdlcursormanager.hpp
+++ b/extern/sdl4ogre/sdlcursormanager.hpp
@@ -1,5 +1,5 @@
-#ifndef _SDL4OGRE_CURSORMANAGER_H
-#define _SDL4OGRE_CURSORMANAGER_H
+#ifndef SDL4OGRE_CURSORMANAGER_H
+#define SDL4OGRE_CURSORMANAGER_H
 
 #include <SDL.h>
 
diff --git a/extern/sdl4ogre/sdlinputwrapper.hpp b/extern/sdl4ogre/sdlinputwrapper.hpp
index a2b698f86..f08e3eff6 100644
--- a/extern/sdl4ogre/sdlinputwrapper.hpp
+++ b/extern/sdl4ogre/sdlinputwrapper.hpp
@@ -1,5 +1,5 @@
-#ifndef _SDL4OGRE_SDLINPUTWRAPPER_H
-#define _SDL4OGRE_SDLINPUTWRAPPER_H
+#ifndef SDL4OGRE_SDLINPUTWRAPPER_H
+#define SDL4OGRE_SDLINPUTWRAPPER_H
 
 #include <SDL_events.h>
 
diff --git a/libs/openengine/bullet/BtOgreExtras.h b/libs/openengine/bullet/BtOgreExtras.h
index b20a3ff98..9572b8a7b 100644
--- a/libs/openengine/bullet/BtOgreExtras.h
+++ b/libs/openengine/bullet/BtOgreExtras.h
@@ -13,8 +13,8 @@
  * =====================================================================================
  */
 
-#ifndef _BtOgreShapes_H_
-#define _BtOgreShapes_H_
+#ifndef BtOgreShapes_H_
+#define BtOgreShapes_H_
 
 #include "btBulletDynamicsCommon.h"
 #include "OgreSimpleRenderable.h"
diff --git a/libs/openengine/bullet/BtOgreGP.h b/libs/openengine/bullet/BtOgreGP.h
index 4ce2f181e..dde606a4f 100644
--- a/libs/openengine/bullet/BtOgreGP.h
+++ b/libs/openengine/bullet/BtOgreGP.h
@@ -14,8 +14,8 @@
  * =====================================================================================
  */
 
-#ifndef _BtOgrePG_H_
-#define _BtOgrePG_H_
+#ifndef BtOgrePG_H_
+#define BtOgrePG_H_
 
 #include "btBulletDynamicsCommon.h"
 #include "BtOgreExtras.h"
diff --git a/libs/openengine/bullet/BtOgrePG.h b/libs/openengine/bullet/BtOgrePG.h
index 9ff069a8f..2e42fe1f9 100644
--- a/libs/openengine/bullet/BtOgrePG.h
+++ b/libs/openengine/bullet/BtOgrePG.h
@@ -14,8 +14,8 @@
  * =====================================================================================
  */
 
-#ifndef _BtOgreGP_H_
-#define _BtOgreGP_H_
+#ifndef BtOgreGP_H_
+#define BtOgreGP_H_
 
 #include "btBulletDynamicsCommon.h"
 #include "OgreSceneNode.h"
diff --git a/libs/openengine/bullet/BulletShapeLoader.h b/libs/openengine/bullet/BulletShapeLoader.h
index 98cda859d..0e5c65226 100644
--- a/libs/openengine/bullet/BulletShapeLoader.h
+++ b/libs/openengine/bullet/BulletShapeLoader.h
@@ -1,5 +1,5 @@
-#ifndef _BULLET_SHAPE_LOADER_H_
-#define _BULLET_SHAPE_LOADER_H_
+#ifndef OPENMW_BULLET_SHAPE_LOADER_H_
+#define OPENMW_BULLET_SHAPE_LOADER_H_
 
 #include <OgreResource.h>
 #include <OgreResourceManager.h>