diff --git a/src/openttd.cpp b/src/openttd.cpp
--- a/src/openttd.cpp
+++ b/src/openttd.cpp
@@ -64,6 +64,7 @@
 #include "engine_base.h"
 #include "engine_func.h"
 #include "core/random_func.hpp"
+#include "rail_gui.h"
 
 #include "newgrf_commons.h"
 
@@ -87,7 +88,6 @@ void CallWindowTickEvent();
 extern void SetDifficultyLevel(int mode, DifficultySettings *gm_opt);
 extern Company *DoStartupNewCompany(bool is_ai, CompanyID company = INVALID_COMPANY);
 extern void ShowOSErrorBox(const char *buf, bool system);
-extern void InitializeRailGUI();
 
 /**
  * Error handling for fatal user errors.
diff --git a/src/rail_gui.h b/src/rail_gui.h
--- a/src/rail_gui.h
+++ b/src/rail_gui.h
@@ -17,5 +17,6 @@
 void ShowBuildRailToolbar(RailType railtype, int button);
 void ReinitGuiAfterToggleElrail(bool disable);
 bool ResetSignalVariant(int32 = 0);
+void InitializeRailGUI();
 
 #endif /* RAIL_GUI_H */
diff --git a/src/saveload/afterload.cpp b/src/saveload/afterload.cpp
--- a/src/saveload/afterload.cpp
+++ b/src/saveload/afterload.cpp
@@ -51,6 +51,7 @@
 #include "../newgrf.h"
 #include "../engine_base.h"
 #include "../engine_func.h"
+#include "../rail_gui.h"
 
 #include "table/strings.h"
 
@@ -60,7 +61,6 @@
 
 extern StringID _switch_mode_errorstr;
 extern Company *DoStartupNewCompany(bool is_ai, CompanyID company = INVALID_COMPANY);
-extern void InitializeRailGUI();
 
 /**
  * Makes a tile canal or water depending on the surroundings.