diff --git a/src/airport_gui.cpp b/src/airport_gui.cpp
index 181744adc3..991c579f05 100644
--- a/src/airport_gui.cpp
+++ b/src/airport_gui.cpp
@@ -156,7 +156,7 @@ enum {
 	BAW_STR_INTERCONTINENTAL_AIRPORT,
 	BAW_HELISTATION,
 	BAW_LAST_AIRPORT = BAW_HELISTATION,
-	BAW_AIRPORT_COUNT = BAW_LAST_AIRPORT - BAW_SMALL_AIRPORT,
+	BAW_AIRPORT_COUNT = BAW_LAST_AIRPORT - BAW_SMALL_AIRPORT + 1,
 	BAW_BTN_DONTHILIGHT = BAW_LAST_AIRPORT + 1,
 	BAW_BTN_DOHILIGHT,
 };