diff --git a/tests/core/dune b/tests/core/dune
index 3bb08d4c..4c4c96a4 100644
--- a/tests/core/dune
+++ b/tests/core/dune
@@ -1,6 +1,6 @@
 (test
  (name t)
- (flags :standard -strict-sequence -warn-error -a+8)
+ (flags :standard -strict-sequence -warn-error -a+8 -open CCShims_)
  (modes native)
  (libraries containers containers.bencode containers.unix threads
    containers_testlib iter gen uutf))