diff --git a/hasty-hamiltonian.cabal b/hasty-hamiltonian.cabal
--- a/hasty-hamiltonian.cabal
+++ b/hasty-hamiltonian.cabal
@@ -1,5 +1,5 @@
 name:                hasty-hamiltonian
-version:             1.1.4
+version:             1.1.5
 synopsis:            Speedy traversal through parameter space.
 homepage:            http://github.com/jtobin/hasty-hamiltonian
 license:             MIT
@@ -54,8 +54,8 @@
     , mwc-probability  >= 1.0.1
     , lens             >= 4 && < 5
     , pipes            >= 4 && < 5
-    , primitive
-    , transformers
+    , primitive        >= 0.5 && < 1.0
+    , transformers     >= 0.5 && < 1.0
 
 Test-suite booth
   type:                exitcode-stdio-1.0