diff --git a/Data/Monoid/Factorial.hs b/Data/Monoid/Factorial.hs
--- a/Data/Monoid/Factorial.hs
+++ b/Data/Monoid/Factorial.hs
@@ -144,6 +144,7 @@
    drop n p = snd (splitAt n p)
    take n p = fst (splitAt n p)
    reverse = mconcat . List.reverse . factors
+   {-# MINIMAL factors | splitPrimePrefix #-}
 
 -- | A subclass of 'FactorialMonoid' whose instances satisfy this additional law:
 --
diff --git a/monoid-subclasses.cabal b/monoid-subclasses.cabal
--- a/monoid-subclasses.cabal
+++ b/monoid-subclasses.cabal
@@ -1,5 +1,5 @@
 Name:                monoid-subclasses
-Version:             0.3.6
+Version:             0.3.6.1
 Cabal-Version:       >= 1.10
 Build-Type:          Simple
 Synopsis:            Subclasses of Monoid
@@ -24,7 +24,7 @@
   Exposed-Modules:   Data.Monoid.Cancellative, Data.Monoid.Factorial, Data.Monoid.Null, Data.Monoid.Textual,
                      Data.Monoid.Instances.ByteString.UTF8, Data.Monoid.Instances.Concat,
                      Data.Monoid.Instances.Measured, Data.Monoid.Instances.Positioned, Data.Monoid.Instances.Stateful
-  Build-Depends:     base < 5, bytestring >= 0.9 && < 1.0, containers == 0.5.*, text >= 0.11 && < 1.2,
+  Build-Depends:     base < 5, bytestring >= 0.9 && < 1.0, containers == 0.5.*, text >= 0.11 && < 1.3,
                      primes == 0.2.*, vector >= 0.9 && < 0.11
   GHC-prof-options:  -auto-all
   if impl(ghc >= 7.0.0)
@@ -33,7 +33,7 @@
 test-suite Main
   Type:              exitcode-stdio-1.0
   x-uses-tf:         true
-  Build-Depends:     base < 5, bytestring >= 0.9 && < 1.0, containers == 0.5.*, text >= 0.11 && < 1.2,
+  Build-Depends:     base < 5, bytestring >= 0.9 && < 1.0, containers == 0.5.*, text >= 0.11 && < 1.3,
                      primes == 0.2.*, vector >= 0.9 && < 0.11, QuickCheck == 2.*, quickcheck-instances == 0.3.*,
                      test-framework >= 0.4.1, test-framework-quickcheck2
   Main-is:           Test/TestMonoidSubclasses.hs