diff --git a/src/cargopacket.cpp b/src/cargopacket.cpp
index 3820d8c772..54cc9b7f7d 100644
--- a/src/cargopacket.cpp
+++ b/src/cargopacket.cpp
@@ -478,7 +478,7 @@ bool VehicleCargoList::Stage(bool accepted, StationID current_station, StationID
 				FlowStat new_shares = flow_it->second;
 				new_shares.ChangeShare(current_station, INT_MIN);
 				StationIDStack excluded = next_station;
-				while (!excluded.IsEmpty()) {
+				while (!excluded.IsEmpty() && !new_shares.GetShares()->empty()) {
 					new_shares.ChangeShare(excluded.Pop(), INT_MIN);
 				}
 				if (new_shares.GetShares()->empty()) {
diff --git a/src/station_cmd.cpp b/src/station_cmd.cpp
index 423907a8f8..ca0c0be05a 100644
--- a/src/station_cmd.cpp
+++ b/src/station_cmd.cpp
@@ -4228,6 +4228,7 @@ void FlowStat::ChangeShare(StationID st, int flow)
  */
 void FlowStat::RestrictShare(StationID st)
 {
+	assert(!this->shares.empty());
 	uint flow = 0;
 	uint last_share = 0;
 	SharesMap new_shares;
@@ -4248,6 +4249,7 @@ void FlowStat::RestrictShare(StationID st)
 	if (flow == 0) return;
 	new_shares[last_share + flow] = st;
 	this->shares.swap(new_shares);
+	assert(!this->shares.empty());
 }
 
 /**
@@ -4257,6 +4259,7 @@ void FlowStat::RestrictShare(StationID st)
  */
 void FlowStat::ReleaseShare(StationID st)
 {
+	assert(!this->shares.empty());
 	uint flow = 0;
 	uint next_share = 0;
 	bool found = false;
@@ -4283,6 +4286,7 @@ void FlowStat::ReleaseShare(StationID st)
 		}
 	}
 	this->shares.swap(new_shares);
+	assert(!this->shares.empty());
 }
 
 /**