diff --git a/src/misc_gui.cpp b/src/misc_gui.cpp
index 5db7b91a33..4316adc7d9 100644
--- a/src/misc_gui.cpp
+++ b/src/misc_gui.cpp
@@ -713,8 +713,6 @@ public:
 	~ErrmsgWindow()
 	{
 		SetRedErrorSquare(INVALID_TILE);
-		extern StringID _switch_mode_errorstr;
-		_switch_mode_errorstr = INVALID_STRING_ID;
 	}
 
 	virtual EventState OnKeyPress(uint16 key, uint16 keycode)
diff --git a/src/openttd.cpp b/src/openttd.cpp
index 73c3b2e5bf..ef7e356eac 100644
--- a/src/openttd.cpp
+++ b/src/openttd.cpp
@@ -1103,6 +1103,7 @@ void SwitchToMode(SwitchMode new_mode)
 
 	if (_switch_mode_errorstr != INVALID_STRING_ID) {
 		ShowErrorMessage(_switch_mode_errorstr, INVALID_STRING_ID, WL_CRITICAL);
+		_switch_mode_errorstr = INVALID_STRING_ID;
 	}
 }