diff --git a/src/rail_cmd.cpp b/src/rail_cmd.cpp
index b1b6ae83b7..02a999eca9 100644
--- a/src/rail_cmd.cpp
+++ b/src/rail_cmd.cpp
@@ -821,10 +821,12 @@ CommandCost CmdBuildSingleRail(TileIndex tile, DoCommandFlag flags, uint32 p1, u
 						Company::Get(_current_company)->infrastructure.rail[railtype] += LEVELCROSSING_TRACKBIT_FACTOR;
 						DirtyCompanyInfrastructureWindows(_current_company);
 						if (num_new_road_pieces > 0 && Company::IsValidID(road_owner)) {
+							assert(roadtype_road != INVALID_ROADTYPE);
 							Company::Get(road_owner)->infrastructure.road[roadtype_road] += num_new_road_pieces;
 							DirtyCompanyInfrastructureWindows(road_owner);
 						}
 						if (num_new_tram_pieces > 0 && Company::IsValidID(tram_owner)) {
+							assert(roadtype_tram != INVALID_ROADTYPE);
 							Company::Get(tram_owner)->infrastructure.road[roadtype_tram] += num_new_tram_pieces;
 							DirtyCompanyInfrastructureWindows(tram_owner);
 						}
diff --git a/src/road_cmd.cpp b/src/road_cmd.cpp
index 3a48e7e512..fdb349aa96 100644
--- a/src/road_cmd.cpp
+++ b/src/road_cmd.cpp
@@ -2915,6 +2915,8 @@ static void ConvertRoadTypeOwner(TileIndex tile, uint num_pieces, Owner owner, R
 	// We can't get a company from invalid owners but we can get ownership of roads without an owner
 	if (owner >= MAX_COMPANIES && owner != OWNER_NONE) return;
 
+	assert(from_type != INVALID_ROADTYPE && to_type != INVALID_ROADTYPE);
+
 	Company *c;
 
 	switch (owner) {