diff --git a/test/src/emacs-module-tests.el b/test/src/emacs-module-tests.el
index 6e309a72edb..4ec1f71bf36 100644
--- a/test/src/emacs-module-tests.el
+++ b/test/src/emacs-module-tests.el
@@ -155,10 +155,26 @@ changes."
       (setq res (concat res s)))
     res))
 
+;; strange code for use in subprocesses
+(progn
+  (eval-and-compile
+    (defun module--define-gc-form ()
+      '(defun module--gc ()
+         (cond ((fboundp 'igc--collect)
+                (igc--collect)
+                (igc--process-messages))
+               (t
+                (garbage-collect))))))
+
+  (defmacro module--define-gc-macro ()
+    (module--define-gc-form))
+
+  (module--define-gc-macro))
+
 (ert-deftest mod-test-globref-make-test ()
   (let ((mod-str (mod-test-globref-make))
         (ref-str (multiply-string "abcdefghijklmnopqrstuvwxyz" 100)))
-    (garbage-collect) ;; XXX: not enough to really test but it's something..
+    (module--gc) ;; XXX: not enough to really test but it's something..
     (should (string= ref-str mod-str))))
 
 (ert-deftest mod-test-globref-free-test ()
@@ -228,6 +244,7 @@ must evaluate to a regular expression string."
                                     ,(prin1-to-string
                                       `(progn
                                          (require 'mod-test ,mod-test-file)
+                                         ,(module--define-gc-form)
                                          ,@body)))))
          ;; Aborting doesn't raise a signal on MS-DOS/Windows, but
          ;; rather exits with a non-zero status: 2 on MS-DOS (see
@@ -283,15 +300,15 @@ should nevertheless detect the invalid load."
   "Check that -module-assertions prevents calling Emacs functions
 during garbage collection."
   :tags (if (getenv "EMACS_EMBA_CI") '(:unstable))
-  (skip-unless (and
-                (not (fboundp 'igc--collect))
-                (or (file-executable-p mod-test-emacs)
-                    (and (eq system-type 'windows-nt)
-                         (file-executable-p (concat mod-test-emacs ".exe"))))))
+  :expected-result (if (fboundp 'igc--collect) :failed :passed)
+  (skip-unless
+   (or (file-executable-p mod-test-emacs)
+       (and (eq system-type 'windows-nt)
+            (file-executable-p (concat mod-test-emacs ".exe")))))
   (module--test-assertion
       (rx "Module function called during garbage collection\n")
     (mod-test-invalid-finalizer)
-    (garbage-collect)))
+    (module--gc)))
 
 (ert-deftest module--test-assertions--globref-invalid-free ()
   "Check that -module-assertions detects invalid freeing of a
@@ -303,7 +320,7 @@ local reference."
   (module--test-assertion
       (rx "Global value was not found in list of " (+ digit) " globals")
     (mod-test-globref-invalid-free)
-    (garbage-collect)))
+    (module--gc)))
 
 (ert-deftest module/describe-function-1 ()
   "Check that Bug#30163 is fixed."
@@ -437,7 +454,6 @@ See Bug#36226."
       (delete-file so))))
 
 (ert-deftest module/function-finalizer ()
-  :expected-result (if (featurep 'mps) :failed :passed)
   "Test that module function finalizers are properly called."
   ;; We create and leak a couple of module functions with attached
   ;; finalizer.  Creating only one function risks spilling it to the
@@ -449,7 +465,7 @@ See Bug#36226."
   (cl-destructuring-bind (valid-before invalid-before)
       (mod-test-function-finalizer-calls)
     (should (zerop invalid-before))
-    (garbage-collect)
+    (module--gc)
     (cl-destructuring-bind (valid-after invalid-after)
         (mod-test-function-finalizer-calls)
       (should (zerop invalid-after))