diff --git a/genex/genex.c b/genex/genex.c
index 29cd9f5..9649ace 100644
--- a/genex/genex.c
+++ b/genex/genex.c
@@ -22,7 +22,8 @@
 static void usage(const char *name)
 {
 	fprintf(stderr,
-"usage: %s [-L libdir ...] [-l lib ...] hierarchy [descriptions ...]\n\n"
+"usage: %s [-d] [-L libdir ...] [-l lib ...] hierarchy [descriptions ...]\n\n"
+"  -d         dump the tree instead of generating a PDF\n"
 "  -L libdir  search all libraries in the specified directory\n"
 "  -l lib     search the specified component library\n"
     , name);
@@ -34,10 +35,14 @@ int main(int argc, char **argv)
 {
 	FILE *file;
 	int c;
+	int dump = 0;
 	char **arg;
 
-	while ((c = getopt(argc, argv, "L:l:")) != EOF)
+	while ((c = getopt(argc, argv, "dL:l:")) != EOF)
 		switch (c) {
+		case 'd':
+			dump = 1;
+			break;
 		case 'L':
 			add_libdir(optarg);
 			break;
@@ -74,7 +79,9 @@ int main(int argc, char **argv)
 		read_desc(file);
 		fclose(file);
 	}
-//	dump_tree();
-	make_pdf();
+	if (dump)
+		dump_tree();
+	else
+		make_pdf();
 	return 0;
 }