diff --git a/src/core/dune b/src/core/dune
index 0bd4bbc5..fd2dd653 100644
--- a/src/core/dune
+++ b/src/core/dune
@@ -17,7 +17,7 @@
  (public_name containers)
  (wrapped false)
  (modules :standard \ mkshims)
- (preprocess (action (run ./cpp/cpp.exe %{input-file})))
+ (preprocess (action (run %{project_root}/src/core/cpp/cpp.exe %{input-file})))
  (flags :standard -warn-error -a+8 -w -32 -safe-string
         -strict-sequence -nolabels -open CCMonomorphic)
  (libraries seq either containers.monomorphic))