diff --git a/Makefile b/Makefile
index 2badea3b..704b0d3e 100644
--- a/Makefile
+++ b/Makefile
@@ -54,7 +54,7 @@ tippecanoe-decode: decode.o projection.o mvt.o
 	$(CXX) $(PG) $(LIBS) $(FINAL_FLAGS) $(CXXFLAGS) -o $@ $^ $(LDFLAGS) -lm -lz -lsqlite3
 
 tile-join: tile-join.o projection.o pool.o mbtiles.o mvt.o memfile.o
-	$(CXX) $(PG) $(LIBS) $(FINAL_FLAGS) $(CXXFLAGS) -o $@ $^ $(LDFLAGS) -lm -lz -lsqlite3
+	$(CXX) $(PG) $(LIBS) $(FINAL_FLAGS) $(CXXFLAGS) -o $@ $^ $(LDFLAGS) -lm -lz -lsqlite3 -lpthread
 
 %.o: %.c $(ALL_H)
 	$(CC) $(PG) $(INCLUDES) $(FINAL_FLAGS) $(CFLAGS) -c -o $@ $<
diff --git a/tile-join.cpp b/tile-join.cpp
index 4bc77989..ab4a300f 100644
--- a/tile-join.cpp
+++ b/tile-join.cpp
@@ -20,7 +20,7 @@
 std::string dequote(std::string s);
 
 bool pk = false;
-int CPUS;
+size_t CPUS;
 
 struct stats {
 	int minzoom;
@@ -414,7 +414,7 @@ void handle_tasks(std::map<zxy, std::vector<std::string>> &tasks, std::vector<st
 		}
 	}
 
-	for (int i = 0; i < CPUS; i++) {
+	for (size_t i = 0; i < CPUS; i++) {
 		void *retval;
 
 		if (pthread_join(pthreads[i], &retval) != 0) {