diff --git a/ghc-MemoTrie.spec b/ghc-MemoTrie.spec
index 10aeafa..bf08d92 100644
--- a/ghc-MemoTrie.spec
+++ b/ghc-MemoTrie.spec
@@ -23,6 +23,8 @@ BuildRequires:  ghc-rpm-macros-extra
 # Begin cabal-rpm deps:
 #BuildRequires:  ghc-newtype-generics-devel
 # End cabal-rpm deps
+# for newtype-generics:
+BuildRequires:  ghc-transformers-devel
 
 %description
 MemoTrie provides a basis for memoized functions over some domains, using