diff --git a/library/Potoki/Produce.hs b/library/Potoki/Produce.hs
--- a/library/Potoki/Produce.hs
+++ b/library/Potoki/Produce.hs
@@ -15,6 +15,7 @@
   infiniteMVar,
   enumInRange,
   mergeOrdering,
+  unfoldr,
 )
 where
 
diff --git a/potoki.cabal b/potoki.cabal
--- a/potoki.cabal
+++ b/potoki.cabal
@@ -1,7 +1,7 @@
 name:
   potoki
 version:
-  2.1.2
+  2.1.3
 synopsis:
   Simple streaming in IO
 description:
@@ -73,5 +73,5 @@
     Potoki.Produce
     Potoki.Transform
   build-depends:
-    potoki-core >=2.3.1 && <2.4
+    potoki-core >=2.3.3 && <2.4