diff --git a/MantleAPI/include/MantleAPI/Traffic/entity_helper.h b/MantleAPI/include/MantleAPI/Traffic/entity_helper.h
index 28dba80691e5248c3df99b8c745967187b9fd8e7..5b743feabc6fedb077298d97ff9e63d13c3ab9c9 100644
--- a/MantleAPI/include/MantleAPI/Traffic/entity_helper.h
+++ b/MantleAPI/include/MantleAPI/Traffic/entity_helper.h
@@ -22,7 +22,7 @@
 namespace mantle_api
 {
 
-void SetSpeed(mantle_api::IEntity* entity, double velocity)
+inline void SetSpeed(mantle_api::IEntity* entity, double velocity)
 {
     auto orientation = entity->GetOrientation();