diff --git a/.travis.yml b/.travis.yml
index d765fe2..fae0096 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -15,6 +15,10 @@ matrix:
   - env: STACK='stack --resolver=lts-13.0' CACHE_NAME=8.6.3
     addons: {apt: {packages: [libgmp-dev]}}
 
+    # nightly
+  - env: STACK='stack --resolver=nightly' CACHE_NAME=nightly
+    addons: {apt: {packages: [libgmp-dev]}}
+
     # Use the resolver in stack.yaml
   - env: STACK=stack CACHE_NAME=stack-linux
     addons: {apt: {packages: [libgmp-dev]}}
@@ -31,7 +35,7 @@ install:
  - ./.travis/install-stack.sh
 
 script:
- - echo "$(stack ghc -- --version) [$(stack ghc -- --print-project-git-commit-id 2> /dev/null || echo '?')]"
+ - echo "$($STACK ghc -- --version) [$($STACK ghc -- --print-project-git-commit-id 2> /dev/null || echo '?')]"
  - GHC_OPTIONS="-Werror"
  - |
    set -ex
diff --git a/.travis/install-stack.sh b/.travis/install-stack.sh
index 1f6417c..55ebf97 100755
--- a/.travis/install-stack.sh
+++ b/.travis/install-stack.sh
@@ -26,4 +26,4 @@ else
   travis_retry fetch_stack_linux
 fi
 
-travis_retry stack --no-terminal setup;
+travis_retry $STACK --no-terminal setup;
diff --git a/ChangeLog.md b/ChangeLog.md
index afd8705..c843352 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,12 @@
 # Changelog for polysemy
 
+## 0.1.2.1 (2019-05-18)
+
+- Give explicit package bounds for dependencies
+- Haddock improvements
+- Remove `Typeable` machinery from `Polysemy.Internal.Union` (thanks to
+    @googleson78)
+
 ## 0.1.2.0 (2019-04-26)
 
 - `runInputAsReader`, `runTraceAsOutput` and `runOutputAsWriter` have more
diff --git a/package.yaml b/package.yaml
index f7066e9..39cd312 100644
--- a/package.yaml
+++ b/package.yaml
@@ -1,5 +1,5 @@
 name:                polysemy
-version:             0.1.2.0
+version:             0.1.2.1
 github:              "isovector/polysemy"
 license:             BSD3
 author:              "Sandy Maguire"
@@ -17,11 +17,11 @@ description:         Please see the README on GitHub at <https://github.com/isov
 
 dependencies:
 - base >= 4.7 && < 5
-- transformers
-- mtl
-- template-haskell
-- syb
-- random
+- transformers >= 0.5.5.0 && < 0.6
+- mtl >= 2.2.2 && <3
+- template-haskell >= 2.14.0.0 && <2.15
+- syb >= 0.7 && <0.8
+- random >= 1.1 && <1.2
 
 default-extensions:
   - DataKinds
@@ -75,8 +75,8 @@ tests:
     - -with-rtsopts=-N
     dependencies:
     - polysemy
-    - inspection-testing
-    - hspec
+    - inspection-testing >= 0.4.1.1 && < 0.5
+    - hspec >= 2.6.0 && < 3
 
 benchmarks:
   polysemy-bench:
diff --git a/polysemy-plugin/package.yaml b/polysemy-plugin/package.yaml
index ff70a6a..839fd68 100644
--- a/polysemy-plugin/package.yaml
+++ b/polysemy-plugin/package.yaml
@@ -1,5 +1,5 @@
 name:                polysemy-plugin
-version:             0.1.0.0
+version:             0.1.0.1
 github:              "isovector/polysemy"
 license:             BSD3
 author:              "Sandy Maguire"
@@ -17,9 +17,9 @@ description:         Please see the README on GitHub at <https://github.com/isov
 
 dependencies:
 - base >= 4.7 && < 5
-- ghc
-- ghc-tcplugins-extra
-- polysemy
+- ghc >= 8.6.3 && < 8.7
+- ghc-tcplugins-extra >= 0.3 && < 0.4
+- polysemy >= 0.1
 
 library:
   source-dirs: src
@@ -35,8 +35,8 @@ tests:
     - -fplugin=Polysemy.Plugin
     dependencies:
     - polysemy-plugin
-    - hspec
-    - should-not-typecheck
+    - hspec >= 2.6.0 && < 3
+    - should-not-typecheck >= 2.1.0 && < 3
 
 default-extensions:
   - DataKinds
diff --git a/polysemy.cabal b/polysemy.cabal
index debdd16..5f786c0 100644
--- a/polysemy.cabal
+++ b/polysemy.cabal
@@ -4,7 +4,7 @@ cabal-version: 1.12
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 5083f650624e23b69f32959147328d1059db99da44a999e30f1a3effd286c3c4
+-- hash: 636a71a55069d695c2cd1817011316cd69fb6c519741a019269b0989b46eb83b
 
 name:           polysemy
 version:        0.1.2.0
@@ -71,11 +71,11 @@ library
   ghc-options: -O2 -Wall
   build-depends:
       base >=4.7 && <5
-    , mtl
-    , random
-    , syb
-    , template-haskell
-    , transformers
+    , mtl >=2.2.2 && <3
+    , random >=1.1 && <1.2
+    , syb >=0.7 && <0.8
+    , template-haskell >=2.14.0.0 && <2.15
+    , transformers >=0.5.5.0 && <0.6
   if flag(dump-core)
     ghc-options: -fplugin=DumpCore -fplugin-opt DumpCore:core-html
     build-depends:
@@ -97,14 +97,14 @@ test-suite polysemy-test
   ghc-options: -threaded -rtsopts -with-rtsopts=-N
   build-depends:
       base >=4.7 && <5
-    , hspec
-    , inspection-testing
-    , mtl
+    , hspec >=2.6.0 && <3
+    , inspection-testing >=0.4.1.1 && <0.5
+    , mtl >=2.2.2 && <3
     , polysemy
-    , random
-    , syb
-    , template-haskell
-    , transformers
+    , random >=1.1 && <1.2
+    , syb >=0.7 && <0.8
+    , template-haskell >=2.14.0.0 && <2.15
+    , transformers >=0.5.5.0 && <0.6
   default-language: Haskell2010
 
 benchmark polysemy-bench
@@ -123,8 +123,8 @@ benchmark polysemy-bench
     , freer-simple
     , mtl
     , polysemy
-    , random
-    , syb
-    , template-haskell
-    , transformers
+    , random >=1.1 && <1.2
+    , syb >=0.7 && <0.8
+    , template-haskell >=2.14.0.0 && <2.15
+    , transformers >=0.5.5.0 && <0.6
   default-language: Haskell2010