diff --git a/cover/tests/main.rkt b/cover/tests/main.rkt
index 73efd5a..0d47a46 100644
--- a/cover/tests/main.rkt
+++ b/cover/tests/main.rkt
@@ -54,7 +54,11 @@
          (cons a (ranges->numbers (cons (list (add1 a) b) r))))]))
 
 (module+ test
-  (define-runtime-path-list test-dirs '("basic" "simple-multi" "syntax" "at-exp" "multibyte-coverage"))
+  (define-runtime-path-list test-dirs (list* "basic" "simple-multi" "syntax" "at-exp"
+                                             ;; submodules don't work prior to this version!
+                                             (if (version<=? (version) "6.2.900")
+                                                 null
+                                                 "multibyte-coverage")))
   (for-each (compose test-dir path->string) test-dirs)
   (define-runtime-path submods "submods")
   (parameterize ([irrelevant-submodules null])