diff --git a/src/ai/ai_gui.hpp b/src/ai/ai_gui.hpp
--- a/src/ai/ai_gui.hpp
+++ b/src/ai/ai_gui.hpp
@@ -18,7 +18,9 @@
 void ShowAIDebugWindow(CompanyID show_company = INVALID_COMPANY);
 void ShowAIConfigWindow();
 void ShowAIDebugWindowIfAIError();
+void InitializeAIGui();
 #else
+#include "../gui.h"
 #include "table/strings.h"
 
 static inline void ShowAIConfigWindow()
@@ -27,6 +29,7 @@ static inline void ShowAIConfigWindow()
 }
 static inline void ShowAIDebugWindow(CompanyID show_company = INVALID_COMPANY) {ShowAIConfigWindow();}
 static inline void ShowAIDebugWindowIfAIError() {}
+static inline void InitializeAIGui() {}
 #endif /* ENABLE_AI */
 
 #endif /* AI_GUI_HPP */
diff --git a/src/misc.cpp b/src/misc.cpp
--- a/src/misc.cpp
+++ b/src/misc.cpp
@@ -14,6 +14,7 @@
 #include "news_func.h"
 #include "variables.h"
 #include "ai/ai.hpp"
+#include "ai/ai_gui.hpp"
 #include "newgrf_house.h"
 #include "group.h"
 #include "economy_func.h"
@@ -41,7 +42,6 @@ void InitializeRailGui();
 void InitializeRoadGui();
 void InitializeAirportGui();
 void InitializeDockGui();
-void InitializeAIGui();
 void InitializeIndustries();
 void InitializeTowns();
 void InitializeSubsidies();