diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright (c) 2018-2019, Balazs Komuves
+Copyright (c) 2018-2022, Balazs Komuves
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
diff --git a/polynomial-algebra.cabal b/polynomial-algebra.cabal
--- a/polynomial-algebra.cabal
+++ b/polynomial-algebra.cabal
@@ -1,17 +1,17 @@
 cabal-version:        2.4
 Name:                 polynomial-algebra
-Version:              0.1
+Version:              0.1.0.1
 Synopsis:             Multivariate polynomial rings
 Description:          Multivariate and univariate polynomial rings, with several different representations
 License:              BSD-3-Clause
 License-file:         LICENSE
 Author:               Balazs Komuves
-Copyright:            (c) 2018-2019 Balazs Komuves
+Copyright:            (c) 2018-2022 Balazs Komuves
 Maintainer:           bkomuves (plus) hackage (at) gmail (dot) com
 Homepage:             https://github.com/bkomuves/polynomial-algebra
 Stability:            Experimental
 Category:             Math
-Tested-With:          GHC == 8.6.5
+Tested-With:          GHC == 8.6.5, GHC == 9.0.1
 Build-Type:           Simple
 
 extra-source-files:   README.md
diff --git a/src/Math/Algebra/Polynomial/Misc.hs b/src/Math/Algebra/Polynomial/Misc.hs
--- a/src/Math/Algebra/Polynomial/Misc.hs
+++ b/src/Math/Algebra/Polynomial/Misc.hs
@@ -247,10 +247,10 @@
   pairs ((x:xs):ys:t) = (x : union xs ys) : pairs t 
   wheel = 2:4:2:4:6:2:6:4:2:4:6:6:2:6:4:2:6:4:6:8:4:2:4:2:  
           4:8:6:4:6:2:4:6:2:6:6:4:2:4:6:2:6:4:2:4:2:10:2:10:wheel 
-  gaps k ws@(w:t) cs@ ~(c:u) 
+  gaps k ws@(w:t) cs@(~(c:u))
     | k==c  = gaps (k+w) t u              
     | True  = k : gaps (k+w) t cs  
-  roll k ws@(w:t) ps@ ~(p:u) 
+  roll k ws@(w:t) ps@(~(p:u)) 
     | k==p  = scanl (\c d->c+p*d) (p*p) ws : roll (k+w) t u              
     | True  = roll (k+w) t ps