diff --git a/src/userprog/syscall.c b/src/userprog/syscall.c
index 5fec7d3..6e7fb17 100644
--- a/src/userprog/syscall.c
+++ b/src/userprog/syscall.c
@@ -10,12 +10,24 @@ static void syscall_handler (struct intr_frame *);
 /* A syscall_function is a function that receives up to 3 arguments, the
    arguments to the functions are either ints or pointers taking up to 32 bits
    in size. */
-typedef uintptr_t syscall_function (uintptr_t, uintptr_t, uintptr_t);
+typedef uintptr_t (*syscall_function) (uintptr_t, uintptr_t, uintptr_t);
 
 /* System Call Functions */
 static void halt (void);
 static void exit (int status);
 
+/* A struct defining a pair of a syscall_function along with its arity. */
+typedef struct {
+  syscall_function function;
+  int arity;
+} syscall_arguments;
+
+/* A look-up table for system call functions mapped using their numbers. */
+static const syscall_arguments syscall_lookup[] = {
+  [SYS_HALT] = {(syscall_function) halt, 0},
+  [SYS_EXIT] = {(syscall_function) exit, 1},
+};
+
 void
 syscall_init (void) 
 {