diff --git a/src/vehicle.cpp b/src/vehicle.cpp
--- a/src/vehicle.cpp
+++ b/src/vehicle.cpp
@@ -723,7 +723,7 @@ bool Vehicle::IsEngineCountable() const
 
 /**
  * Check whether Vehicle::engine_type has any meaning.
- * @return true if the vehicle has a useable engine type.
+ * @return true if the vehicle has a usable engine type.
  */
 bool Vehicle::HasEngineType() const
 {