Cannot use --load in SBCL

[IanDavey]

Consider the following bare-bones tests.lisp:

(ql:quickload "lift")
(use-package :lift)
(deftestsuite a-simple-test () ())

Upon running sbcl --load tests.lisp, I get the following:

debugger invoked on a TYPE-ERROR in thread
#<THREAD "main thread" RUNNING {1002DB2B43}>:
  The value
    NIL
  is not of type
    (OR (VECTOR CHARACTER) (VECTOR NIL) BASE-STRING PATHNAME FILE-STREAM)
  when binding PATHNAME

This is on Windows 10 and SBCL 1.3.15, if that makes a difference.