diff --git a/library/Potoki/Core/Transform/Concurrency.hs b/library/Potoki/Core/Transform/Concurrency.hs
--- a/library/Potoki/Core/Transform/Concurrency.hs
+++ b/library/Potoki/Core/Transform/Concurrency.hs
@@ -12,7 +12,7 @@
 bufferizeFlushing :: Int -> Transform input [input]
 bufferizeFlushing maxSize =
   Transform $ \ (A.Fetch fetchIO) -> liftIO $ do
-    buffer <- newTBQueueIO maxSize
+    buffer <- newTBQueueIO (fromIntegral maxSize)
     activeVar <- newTVarIO True
 
     forkIO $ let
@@ -39,7 +39,7 @@
 bufferize :: NFData element => Int -> Transform element element
 bufferize size =
   Transform $ \ (A.Fetch fetchIO) -> liftIO $ do
-    buffer <- newTBQueueIO size
+    buffer <- newTBQueueIO (fromIntegral size)
     activeVar <- newTVarIO True
 
     forkIO $ let
@@ -103,7 +103,7 @@
 unsafeConcurrently :: NFData output => Int -> Transform input output -> Transform input output
 unsafeConcurrently workersAmount (Transform syncTransformIO) = 
   Transform $ \ fetchIO -> liftIO $ do
-    chan <- newTBQueueIO (workersAmount * 2)
+    chan <- newTBQueueIO (fromIntegral (workersAmount * 2))
     workersCounter <- newTVarIO workersAmount
 
     replicateM_ workersAmount $ forkIO $ do
@@ -130,7 +130,7 @@
 
 concurrentlyInOrder :: NFData b => Int -> Transform a b -> Transform a b
 concurrentlyInOrder concurrency (Transform transform) = Transform $ \ (Fetch fetchA) -> liftIO $ do
-  inputQueue <- newTBQueueIO concurrency
+  inputQueue <- newTBQueueIO (fromIntegral concurrency)
   outputSlotQueue <- newTQueueIO
   liveWorkersVar <- newTVarIO concurrency
 
diff --git a/potoki-core.cabal b/potoki-core.cabal
--- a/potoki-core.cabal
+++ b/potoki-core.cabal
@@ -1,5 +1,5 @@
 name: potoki-core
-version: 2.3.2
+version: 2.3.2.1
 synopsis: Low-level components of "potoki"
 description:
   Provides everything required for building custom instances of
@@ -58,7 +58,7 @@
     profunctors >=5.2 && <6,
     ptr >=0.16.2 && <0.17,
     scanner >=0.3 && <0.4,
-    stm >=2.4 && <3,
+    stm >=2.5 && <2.6,
     text >=1 && <2,
     text-builder >=0.6.3 && <0.7,
     time >=1.5 && <2,