diff --git a/src/C4Include.cpp b/src/C4Include.cpp
index 5c8eef107..4656d61bb 100644
--- a/src/C4Include.cpp
+++ b/src/C4Include.cpp
@@ -119,7 +119,7 @@
 #include "lib/C4NameList.h"
 #include "lib/C4Random.h"
 #include "lib/C4Rect.h"
-#include "lib/C4RTF.H"
+#include "lib/C4RTF.h"
 #include "lib/C4Stat.h"
 #include "lib/Fixed.h"
 #include "lib/PathFinder.h"
diff --git a/src/gui/C4GameLobby.cpp b/src/gui/C4GameLobby.cpp
index 64bd074a0..fcd7116f4 100644
--- a/src/gui/C4GameLobby.cpp
+++ b/src/gui/C4GameLobby.cpp
@@ -28,7 +28,7 @@
 #include "C4Network2Dialogs.h"
 #include "C4GameOptions.h"
 #include "C4GameDialogs.h"
-#include "C4RTF.H"
+#include "C4RTF.h"
 #include "C4ChatDlg.h"
 #include "C4PlayerInfoListBox.h"
 #include <C4MessageInput.h>
diff --git a/src/gui/C4StartupScenSelDlg.cpp b/src/gui/C4StartupScenSelDlg.cpp
index 895b8b5f4..8e2f7fc4b 100644
--- a/src/gui/C4StartupScenSelDlg.cpp
+++ b/src/gui/C4StartupScenSelDlg.cpp
@@ -30,7 +30,7 @@
 #include <C4StartupNetDlg.h>
 #include <C4ComponentHost.h>
 #include <C4Components.h>
-#include <C4RTF.H>
+#include <C4RTF.h>
 #include <C4Log.h>
 #include <C4Game.h>
 #include <C4GameDialogs.h>
diff --git a/src/lib/C4RTF.cpp b/src/lib/C4RTF.cpp
index 45462cb31..df142e9dc 100644
--- a/src/lib/C4RTF.cpp
+++ b/src/lib/C4RTF.cpp
@@ -21,7 +21,7 @@
 
 #include "C4Include.h"
 #include "Standard.h"
-#include "C4RTF.H"
+#include "C4RTF.h"
 
 #include <cctype>
 
diff --git a/xcode/Clonk.xcodeproj/project.pbxproj b/xcode/Clonk.xcodeproj/project.pbxproj
index 4d84ec409..17cf10888 100644
--- a/xcode/Clonk.xcodeproj/project.pbxproj
+++ b/xcode/Clonk.xcodeproj/project.pbxproj
@@ -529,7 +529,7 @@
 		5862E0271032E57A002CAE9E /* C4Random.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = C4Random.cpp; sourceTree = "<group>"; };
 		5862E0281032E57A002CAE9E /* C4Random.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = C4Random.h; sourceTree = "<group>"; };
 		5862E0291032E57A002CAE9E /* C4RTF.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = C4RTF.cpp; sourceTree = "<group>"; };
-		5862E02A1032E57A002CAE9E /* C4RTF.H */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = C4RTF.H; sourceTree = "<group>"; };
+		5862E02A1032E57A002CAE9E /* C4RTF.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = C4RTF.h; sourceTree = "<group>"; };
 		5862E02B1032E57A002CAE9E /* C4Stat.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = C4Stat.cpp; sourceTree = "<group>"; };
 		5862E02C1032E57A002CAE9E /* C4Stat.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = C4Stat.h; sourceTree = "<group>"; };
 		5862E02D1032E57A002CAE9E /* Fixed.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = Fixed.cpp; sourceTree = "<group>"; };
@@ -1237,7 +1237,7 @@
 				5862E0271032E57A002CAE9E /* C4Random.cpp */,
 				5862E0281032E57A002CAE9E /* C4Random.h */,
 				5862E0291032E57A002CAE9E /* C4RTF.cpp */,
-				5862E02A1032E57A002CAE9E /* C4RTF.H */,
+				5862E02A1032E57A002CAE9E /* C4RTF.h */,
 				5862E02B1032E57A002CAE9E /* C4Stat.cpp */,
 				5862E02C1032E57A002CAE9E /* C4Stat.h */,
 				5862E02D1032E57A002CAE9E /* Fixed.cpp */,