diff --git a/src/cli/dune b/src/cli/dune
index a2b111b71..572d1a1e6 100644
--- a/src/cli/dune
+++ b/src/cli/dune
@@ -4,4 +4,4 @@
  (modes byte native)
  (modules :standard)
  (libraries cmdliner lambdapi.lsp lambdapi.tool lambdapi.handle
-            lambdapi.export))
+            lambdapi.export unix))
diff --git a/src/core/dune b/src/core/dune
index d0f25c063..72e38fe0a 100644
--- a/src/core/dune
+++ b/src/core/dune
@@ -10,4 +10,4 @@
  (public_name lambdapi.core)
  (synopsis "LambdaPi interactive theorem prover [core]")
  (modules :standard)
- (libraries lambdapi.common lambdapi.lplib pratter bindlib why3))
+ (libraries lambdapi.common lambdapi.lplib pratter bindlib why3 unix))
diff --git a/src/tool/dune b/src/tool/dune
index d73a042a9..d3cc83495 100644
--- a/src/tool/dune
+++ b/src/tool/dune
@@ -2,7 +2,7 @@
  (name tool)
  (public_name lambdapi.tool)
  (modules :standard)
- (libraries lambdapi.parsing lambdapi.core dream)
+ (libraries lambdapi.parsing lambdapi.core dream unix)
  (preprocess (pps lwt_ppx)))
 
 (rule