diff --git a/include/ardix/syscall.h b/include/ardix/syscall.h
index 53e28e4..8ed975a 100644
--- a/include/ardix/syscall.h
+++ b/include/ardix/syscall.h
@@ -17,8 +17,7 @@ enum syscall {
 };
 
 /** Perform an indirect system call. */
-int syscall(enum syscall number, sysarg_t arg1, sysarg_t arg2, sysarg_t arg3,
-	    sysarg_t arg4, sysarg_t arg5, sysarg_t arg6);
+int syscall(enum syscall number, ...);
 
 /** The table of system call handlers, indexed by syscall number. */
 extern const int (*sys_table[NSYSCALLS])(sysarg_t arg1, sysarg_t arg2, sysarg_t arg3,
diff --git a/lib/unistd.c b/lib/unistd.c
index 0c840c8..b55e4e1 100644
--- a/lib/unistd.c
+++ b/lib/unistd.c
@@ -10,12 +10,12 @@
 
 __shared ssize_t read(int fildes, void *buf, size_t nbyte)
 {
-	return syscall(SYSCALL_READ, (sysarg_t)fildes, (sysarg_t)buf, (sysarg_t)nbyte, 0, 0, 0);
+	return syscall(SYSCALL_READ, (sysarg_t)fildes, (sysarg_t)buf, (sysarg_t)nbyte);
 }
 
 __shared ssize_t write(int fildes, const void *buf, size_t nbyte)
 {
-	return syscall(SYSCALL_WRITE, (sysarg_t)fildes, (sysarg_t)buf, (sysarg_t)nbyte, 0, 0, 0);
+	return syscall(SYSCALL_WRITE, (sysarg_t)fildes, (sysarg_t)buf, (sysarg_t)nbyte);
 }
 
 /*