diff --git a/tile.cpp b/tile.cpp
index d96a2b0c..edb49dcf 100644
--- a/tile.cpp
+++ b/tile.cpp
@@ -557,7 +557,7 @@ int manage_gap(unsigned long long index, unsigned long long *previndex, double s
 	return 0;
 }
 
-long long write_tile(FILE *geoms, long long *geompos_in, char *metabase, char *stringpool, int z, unsigned tx, unsigned ty, int detail, int min_detail, int basezoom, std::vector<std::string> *layernames, sqlite3 *outdb, double droprate, int buffer, const char *fname, FILE **geomfile, int minzoom, int maxzoom, double todo, volatile long long *along, long long alongminus, double gamma, int nlayers, int child_shards, long long *meta_off, long long *pool_off, unsigned *initial_x, unsigned *initial_y, volatile int *running, double simplification, std::vector<std::map<std::string, layermap_entry> > *layermaps) {
+long long write_tile(FILE *geoms, long long *geompos_in, char *metabase, char *stringpool, int z, unsigned tx, unsigned ty, int detail, int min_detail, int basezoom, std::vector<std::string> *layernames, sqlite3 *outdb, double droprate, int buffer, const char *fname, FILE **geomfile, int minzoom, int maxzoom, double todo, volatile long long *along, long long alongminus, double gamma, int nlayers, int child_shards, long long *meta_off, long long *pool_off, unsigned *initial_x, unsigned *initial_y, volatile int *running, double simplification, std::vector<std::map<std::string, layermap_entry>> *layermaps, std::vector<std::vector<std::string>> *layer_unmaps) {
 	int line_detail;
 	double fraction = 1;
 
@@ -608,7 +608,7 @@ long long write_tile(FILE *geoms, long long *geompos_in, char *metabase, char *s
 		long long unclipped_features = 0;
 
 		std::vector<struct partial> partials;
-		std::vector<std::vector<coalesce> > features;
+		std::vector<std::vector<coalesce>> features;
 		for (int i = 0; i < nlayers; i++) {
 			features.push_back(std::vector<coalesce>());
 		}
@@ -927,6 +927,8 @@ long long write_tile(FILE *geoms, long long *geompos_in, char *metabase, char *s
 					c.id = partials[i].id;
 					c.has_id = partials[i].has_id;
 
+					// printf("segment %d layer %lld is %s\n", partials[i].segment, partials[i].layer, (*layer_unmaps)[partials[i].segment][partials[i].layer].c_str());
+
 					features[layer].push_back(c);
 				}
 			}
@@ -1155,7 +1157,8 @@ struct write_tile_args {
 	unsigned *initial_y;
 	volatile int *running;
 	int err;
-	std::vector<std::map<std::string, layermap_entry> > *layermaps;
+	std::vector<std::map<std::string, layermap_entry>> *layermaps;
+	std::vector<std::vector<std::string>> *layer_unmaps;
 };
 
 void *run_thread(void *vargs) {
@@ -1196,7 +1199,7 @@ void *run_thread(void *vargs) {
 
 			// fprintf(stderr, "%d/%u/%u\n", z, x, y);
 
-			long long len = write_tile(geom, &geompos, arg->metabase, arg->stringpool, z, x, y, z == arg->maxzoom ? arg->full_detail : arg->low_detail, arg->min_detail, arg->basezoom, arg->layernames, arg->outdb, arg->droprate, arg->buffer, arg->fname, arg->geomfile, arg->minzoom, arg->maxzoom, arg->todo, arg->along, geompos, arg->gamma, arg->nlayers, arg->child_shards, arg->meta_off, arg->pool_off, arg->initial_x, arg->initial_y, arg->running, arg->simplification, arg->layermaps);
+			long long len = write_tile(geom, &geompos, arg->metabase, arg->stringpool, z, x, y, z == arg->maxzoom ? arg->full_detail : arg->low_detail, arg->min_detail, arg->basezoom, arg->layernames, arg->outdb, arg->droprate, arg->buffer, arg->fname, arg->geomfile, arg->minzoom, arg->maxzoom, arg->todo, arg->along, geompos, arg->gamma, arg->nlayers, arg->child_shards, arg->meta_off, arg->pool_off, arg->initial_x, arg->initial_y, arg->running, arg->simplification, arg->layermaps, arg->layer_unmaps);
 
 			if (len < 0) {
 				int *err = &arg->err;
@@ -1247,7 +1250,20 @@ void *run_thread(void *vargs) {
 	return NULL;
 }
 
-int traverse_zooms(int *geomfd, off_t *geom_size, char *metabase, char *stringpool, unsigned *midx, unsigned *midy, std::vector<std::string> &layernames, int maxzoom, int minzoom, int basezoom, sqlite3 *outdb, double droprate, int buffer, const char *fname, const char *tmpdir, double gamma, int nlayers, int full_detail, int low_detail, int min_detail, long long *meta_off, long long *pool_off, unsigned *initial_x, unsigned *initial_y, double simplification, std::vector<std::map<std::string, layermap_entry> > &layermaps) {
+int traverse_zooms(int *geomfd, off_t *geom_size, char *metabase, char *stringpool, unsigned *midx, unsigned *midy, std::vector<std::string> &layernames, int maxzoom, int minzoom, int basezoom, sqlite3 *outdb, double droprate, int buffer, const char *fname, const char *tmpdir, double gamma, int nlayers, int full_detail, int low_detail, int min_detail, long long *meta_off, long long *pool_off, unsigned *initial_x, unsigned *initial_y, double simplification, std::vector<std::map<std::string, layermap_entry>> &layermaps) {
+	// Table to map segment and layer number back to layer name
+	std::vector<std::vector<std::string>> layer_unmaps;
+	for (size_t seg = 0; seg < layermaps.size(); seg++) {
+		layer_unmaps.push_back(std::vector<std::string>());
+
+		for (auto a = layermaps[seg].begin(); a != layermaps[seg].end(); ++a) {
+			if (a->second.id >= layer_unmaps[seg].size()) {
+				layer_unmaps[seg].resize(a->second.id + 1);
+			}
+			layer_unmaps[seg][a->second.id] = a->first;
+		}
+	}
+
 	int i;
 	for (i = 0; i <= maxzoom; i++) {
 		long long most = 0;
@@ -1384,6 +1400,7 @@ int traverse_zooms(int *geomfd, off_t *geom_size, char *metabase, char *stringpo
 			args[thread].initial_x = initial_x;
 			args[thread].initial_y = initial_y;
 			args[thread].layermaps = &layermaps;
+			args[thread].layer_unmaps = &layer_unmaps;
 
 			args[thread].tasks = dispatches[thread].tasks;
 			args[thread].running = &running;