diff --git a/src/group.h b/src/group.h
--- a/src/group.h
+++ b/src/group.h
@@ -76,15 +76,17 @@ static inline uint GetGroupArraySize(voi
  * @param id_e The EngineID of the engine to count
  * @return The number of engines with EngineID id_e in the group
  */
-static inline uint GetGroupNumEngines(GroupID id_g, EngineID id_e)
+static inline uint GetGroupNumEngines(PlayerID p, GroupID id_g, EngineID id_e)
 {
 	if (IsValidGroupID(id_g)) return GetGroup(id_g)->num_engines[id_e];
 
-	uint num = GetPlayer(_local_player)->num_engines[id_e];
+	uint num = GetPlayer(p)->num_engines[id_e];
 	if (!IsDefaultGroupID(id_g)) return num;
 
 	const Group *g;
-	FOR_ALL_GROUPS(g) num -= g->num_engines[id_e];
+	FOR_ALL_GROUPS(g) {
+		if (g->owner == p) num -= g->num_engines[id_e];
+	}
 	return num;
 }