diff --git a/hgeometry-combinatorial.cabal b/hgeometry-combinatorial.cabal
--- a/hgeometry-combinatorial.cabal
+++ b/hgeometry-combinatorial.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                hgeometry-combinatorial
-version:             0.12.0.1
+version:             0.12.0.2
 synopsis:            Data structures, and Data types.
 description:
     The Non-geometric data types and algorithms used in HGeometry.
@@ -149,7 +149,7 @@
               , data-clist              >= 0.1.2.3
               , vector-circular         >= 0.1.2
               , nonempty-vector         >= 0.2.0.0
-              , vector-builder          >= 0.3.7
+              , vector-builder          >= 0.3.7   && <= 0.3.8
               , unordered-containers
 
               , aeson                   >= 1.0
@@ -247,11 +247,16 @@
                       , vector
                       , containers
                       , random
-                      , singletons
                       , filepath
                       , directory
                       , yaml
                       , MonadRandom
+  -- -- Such a mess:
+  -- if impl(ghc == 9.*)
+  --   build-depends:      singletons              == 3.*
+  --                     , singletons-th           == 3.*
+  -- else
+  --   build-depends:      singletons              == 2.*
 
   default-extensions: TypeFamilies
                     , GADTs