diff --git a/src/group_gui.cpp b/src/group_gui.cpp
--- a/src/group_gui.cpp
+++ b/src/group_gui.cpp
@@ -631,7 +631,7 @@ public:
 		switch (widget) {
 			case WID_GL_ALL_VEHICLES: // All vehicles
 			case WID_GL_DEFAULT_VEHICLES: // Ungrouped vehicles
-				DoCommandP(0, DEFAULT_GROUP, this->vehicle_sel, CMD_ADD_VEHICLE_GROUP | CMD_MSG(STR_ERROR_GROUP_CAN_T_ADD_VEHICLE));
+				DoCommandP(0, DEFAULT_GROUP, this->vehicle_sel | (_ctrl_pressed ? 1 << 31 : 0), CMD_ADD_VEHICLE_GROUP | CMD_MSG(STR_ERROR_GROUP_CAN_T_ADD_VEHICLE));
 
 				this->vehicle_sel = INVALID_VEHICLE;
 				this->group_over = INVALID_GROUP;
@@ -648,7 +648,7 @@ public:
 				uint id_g = this->group_sb->GetScrolledRowFromWidget(pt.y, this, WID_GL_LIST_GROUP, 0, this->tiny_step_height);
 				if (id_g >= this->groups.Length()) return;
 
-				DoCommandP(0, this->groups[id_g]->index, vindex, CMD_ADD_VEHICLE_GROUP | CMD_MSG(STR_ERROR_GROUP_CAN_T_ADD_VEHICLE));
+				DoCommandP(0, this->groups[id_g]->index, vindex | (_ctrl_pressed ? 1 << 31 : 0), CMD_ADD_VEHICLE_GROUP | CMD_MSG(STR_ERROR_GROUP_CAN_T_ADD_VEHICLE));
 				break;
 			}