diff --git a/library/user-start.c b/library/user-start.c
new file mode 100644
index 0000000..3358d15
--- /dev/null
+++ b/library/user-start.c
@@ -0,0 +1,23 @@
+/*
+Copyright (C) 2016-2019 The University of Notre Dame
+This software is distributed under the GNU General Public License.
+See the file LICENSE for details.
+*/
+
+/*
+This module is the runtime start of every user-level program.
+The very first symbol in this module must be _start() because
+the kernel simply jumps to the very first location of the executable.
+_start() sets up any necessary runtime environment and invokes
+the main function.  Note that this function cannot exit, but
+must invoke the syscall_process_exit() system call to terminate the process.
+*/
+
+#include "library/syscalls.h"
+
+int main(int argc, const char *argv[]);
+
+void _start(int argc, const char **argv)
+{
+	syscall_process_exit(main(argc, argv));
+}