diff --git a/simconvoi.cc b/simconvoi.cc
index 3ca4ab3a9..9c10033df 100644
--- a/simconvoi.cc
+++ b/simconvoi.cc
@@ -908,7 +908,10 @@ sync_result convoi_t::sync_step(uint32 delta_t)
 				while(sp_soll>>12) {
 					// Attempt to move one step.
 					uint32 sp_hat = fahr[0]->do_drive(1<<YARDS_PER_VEHICLE_STEP_SHIFT);
-					int v_nr = get_vehicle_at_length((++steps_driven)>>4);
+					if(  sp_hat>0  ) {
+						steps_driven++;
+					}
+					int v_nr = get_vehicle_at_length(steps_driven>>4);
 					// stop when depot reached
 					if (state==INITIAL) {
 						return SYNC_REMOVE;
@@ -916,12 +919,17 @@ sync_result convoi_t::sync_step(uint32 delta_t)
 					if (state==ROUTING_1) {
 						break;
 					}
-					// until all are moving or something went wrong (sp_hat==0)
-					if(sp_hat==0  ||  v_nr==anz_vehikel) {
+					
+					if(  v_nr==anz_vehikel  ) {
+						// all are moving
 						steps_driven = -1;
 						state = DRIVING;
 						return SYNC_OK;
 					}
+					else if(  sp_hat==0  ) {
+						// something went wrong. wait for next sync_step()
+						return SYNC_OK;
+					}
 					// now only the right numbers
 					for(int i=1; i<=v_nr; i++) {
 						fahr[i]->do_drive(sp_hat);