diff --git a/src/group_cmd.cpp b/src/group_cmd.cpp
--- a/src/group_cmd.cpp
+++ b/src/group_cmd.cpp
@@ -110,7 +110,7 @@ CommandCost CmdCreateGroup(TileIndex til
 		InvalidateWindowData(GetWCForVT(vt), (vt << 11) | VLW_GROUP_LIST | _current_player);
 	}
 
-	return 0;
+	return CommandCost();
 }
 
 
@@ -156,7 +156,7 @@ CommandCost CmdDeleteGroup(TileIndex til
 		InvalidateWindowData(GetWCForVT(vt), (vt << 11) | VLW_GROUP_LIST | _current_player);
 	}
 
-	return 0;
+	return CommandCost();
 }
 
 
@@ -187,7 +187,7 @@ CommandCost CmdRenameGroup(TileIndex til
 		InvalidateWindowData(GetWCForVT(g->vehicle_type), (g->vehicle_type << 11) | VLW_GROUP_LIST | _current_player);
 	}
 
-	return 0;
+	return CommandCost();
 }
 
 
@@ -235,7 +235,7 @@ CommandCost CmdAddVehicleGroup(TileIndex
 		InvalidateWindowData(GetWCForVT(v->type), (v->type << 11) | VLW_GROUP_LIST | _current_player);
 	}
 
-	return 0;
+	return CommandCost();
 }
 
 /**
@@ -271,7 +271,7 @@ CommandCost CmdAddSharedVehicleGroup(Til
 		InvalidateWindowData(GetWCForVT(type), (type << 11) | VLW_GROUP_LIST | _current_player);
 	}
 
-	return 0;
+	return CommandCost();
 }
 
 
@@ -307,7 +307,7 @@ CommandCost CmdRemoveAllVehiclesGroup(Ti
 		InvalidateWindowData(GetWCForVT(type), (type << 11) | VLW_GROUP_LIST | _current_player);
 	}
 
-	return 0;
+	return CommandCost();
 }
 
 
@@ -332,7 +332,7 @@ CommandCost CmdSetGroupReplaceProtection
 		InvalidateWindowData(GetWCForVT(g->vehicle_type), (g->vehicle_type << 11) | VLW_GROUP_LIST | _current_player);
 	}
 
-	return 0;
+	return CommandCost();
 }
 
 /**