diff --git a/lisp/emacs-lisp/ert.el b/lisp/emacs-lisp/ert.el
index beb32c48ce..f4d2f725ac 100644
--- a/lisp/emacs-lisp/ert.el
+++ b/lisp/emacs-lisp/ert.el
@@ -281,17 +281,19 @@ ert--special-operator-p
          (and (subrp definition)
               (eql (cdr (subr-arity definition)) 'unevalled)))))
 
+(require 'byte-opt)
+
 (defun ert--expand-should-1 (whole form inner-expander)
   "Helper function for the `should' macro and its variants."
   (let ((form
          (condition-case err
-             (macroexpand-all form (append (bound-and-true-p
-                                            byte-compile-macro-environment)
-                                           (cond
-                                            ((boundp 'macroexpand-all-environment)
-                                             macroexpand-all-environment)
-                                            ((boundp 'cl-macro-environment)
-                                             cl-macro-environment))))
+             (byte-compile-inline-expand (macroexpand-all form (append (bound-and-true-p
+                                                                        byte-compile-macro-environment)
+                                                                       (cond
+                                                                        ((boundp 'macroexpand-all-environment)
+                                                                         macroexpand-all-environment)
+                                                                        ((boundp 'cl-macro-environment)
+                                                                         cl-macro-environment)))))
            (error `(signal ',(car err) ',(cdr err))))))
     (cond
      ((or (atom form) (ert--special-operator-p (car form)))
@@ -308,7 +310,8 @@ ert--expand-should-1
         (cl-assert (or (symbolp fn-name)
                        (and (consp fn-name)
                             (eql (car fn-name) 'lambda)
-                            (listp (cdr fn-name)))))
+                            (listp (cdr fn-name)))
+                       (byte-code-function-p fn-name)))
         (let ((fn (cl-gensym "fn-"))
               (args (cl-gensym "args-"))
               (value (cl-gensym "value-"))