diff --git a/src/Driver.hs b/src/Driver.hs
index f24bc74e..6024ca81 100644
--- a/src/Driver.hs
+++ b/src/Driver.hs
@@ -317,7 +317,7 @@ pooledForConcurrentlyIO_ as f = do
               _ <- f a
               go
             )
-  replicateConcurrently_ processCount go
+  replicateConcurrently_ ((processCount + 1) `div` 2) go
 
 pooledForConcurrentlyIO
   :: Traversable t
@@ -344,7 +344,7 @@ pooledForConcurrentlyIO as f = do
               atomicWriteIORef ref result
               go
             )
-  replicateConcurrently_ processCount go
+  replicateConcurrently_ ((processCount + 1) `div` 2) go
   forM jobs $ \(_, ref) ->
     readIORef ref