diff --git a/Makefile.am b/Makefile.am
index 713abd8e85190e24e33171efa014b60ebb7af3af..2f95d16ebd1ce72db2f853e0930e0c2c07a756cd 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1594,11 +1594,9 @@ hlint: $(HS_BUILT_SRCS) htools/lint-hints.hs
 	if tty -s; then C="-c"; else C=""; fi; \
 	$(HLINT) --utf8 --report=doc/hs-lint.html --cross $$C \
 	  --ignore "Use first" \
-	  --ignore "Use comparing" \
-	  --ignore "Use on" \
-	  --ignore "Reduce duplication" \
 	  --ignore "Use &&&" \
 	  --ignore "Use void" \
+	  --ignore "Reduce duplication" \
 	  --hint htools/lint-hints \
 	  $(filter-out $(HLINT_EXCLUDES),$(HS_LIBTEST_SRCS) $(HS_PROG_SRCS))
 
diff --git a/htools/Ganeti/HTools/Node.hs b/htools/Ganeti/HTools/Node.hs
index 24534556db26c0e301879e1676ea6c819c01981d..eff4fb51515970301d3dfa9cce8e50d1fbb4449c 100644
--- a/htools/Ganeti/HTools/Node.hs
+++ b/htools/Ganeti/HTools/Node.hs
@@ -73,14 +73,15 @@ module Ganeti.HTools.Node
   , mkNodeGraph
   ) where
 
-import Data.List hiding (group)
-import qualified Data.Map as Map
+import Control.Monad (liftM, liftM2)
 import qualified Data.Foldable as Foldable
-import qualified Data.IntMap as IntMap
+import Data.Function (on)
 import qualified Data.Graph as Graph
+import qualified Data.IntMap as IntMap
+import Data.List hiding (group)
+import qualified Data.Map as Map
 import Data.Ord (comparing)
 import Text.Printf (printf)
-import Control.Monad (liftM, liftM2)
 
 import qualified Ganeti.HTools.Container as Container
 import qualified Ganeti.HTools.Instance as Instance
@@ -683,5 +684,5 @@ defaultFields =
 computeGroups :: [Node] -> [(T.Gdx, [Node])]
 computeGroups nodes =
   let nodes' = sortBy (comparing group) nodes
-      nodes'' = groupBy (\a b -> group a == group b) nodes'
+      nodes'' = groupBy ((==) `on` group) nodes'
   in map (\nl -> (group (head nl), nl)) nodes''