diff --git a/src/script/api/script_town.cpp b/src/script/api/script_town.cpp
index 3b9a4b7b6b..c098039fdc 100644
--- a/src/script/api/script_town.cpp
+++ b/src/script/api/script_town.cpp
@@ -166,7 +166,7 @@
 
 /* static */ int32 ScriptTown::GetGrowthRate(TownID town_id)
 {
-	if (!IsValidTown(town_id)) return false;
+	if (!IsValidTown(town_id)) return -1;
 
 	const Town *t = ::Town::Get(town_id);
 
diff --git a/src/script/api/script_town.hpp b/src/script/api/script_town.hpp
index d301cbe563..df02f18ac6 100644
--- a/src/script/api/script_town.hpp
+++ b/src/script/api/script_town.hpp
@@ -262,7 +262,7 @@ public:
 	 * Get the amount of days between town growth.
 	 * @param town_id The index of the town.
 	 * @pre IsValidTown(town_id).
-	 * @return True if the action succeeded.
+	 * @return Amount of days between town growth.
 	 * @note This function does not indicate when it will grow next. It only tells you the time between growths.
 	 */
 	static int32 GetGrowthRate(TownID town_id);