diff --git a/dwl.c b/dwl.c
index 5536ec5..5117b38 100644
--- a/dwl.c
+++ b/dwl.c
@@ -2839,6 +2839,8 @@ main(int argc, char *argv[])
 		else if (c == 'e') {
 			autostart_runtime[autostart_runtime_idx] = optarg;
 			autostart_runtime_idx++;
+			autostart_runtime[autostart_runtime_idx] = NULL;
+			autostart_runtime_idx++;
 		}
 		else if (c == 'd')
 			log_level = WLR_DEBUG;