diff --git a/benchmark/hashtable-benchmark.cabal b/benchmark/hashtable-benchmark.cabal
--- a/benchmark/hashtable-benchmark.cabal
+++ b/benchmark/hashtable-benchmark.cabal
@@ -21,20 +21,20 @@
                      base16-bytestring    == 0.1.*,
                      bytestring           >= 0.9     && <0.11,
                      containers           >= 0.4     && <0.6,
-                     criterion            >= 0.8     && <0.9,
+                     criterion            >= 1.2     && <1.3,
                      csv                  == 0.1.*,
-                     deepseq              >= 1.1     && <1.4,
+                     deepseq              >= 1.1     && <1.5,
                      filepath             == 1.*,
                      hashable             >= 1.1 && <1.2 || >= 1.2.1 && <1.3,
                      hashtables           >= 1.2     && <1.3,
                      mtl                  == 2.*,
                      mwc-random           >= 0.8     && <0.14,
                      primitive,
-                     statistics           >= 0.8     && <0.11,
+                     statistics           >= 0.14    && <0.15,
                      threads              >= 0.4     && <0.6,
                      unordered-containers >= 0.2     && <0.3,
-                     vector               >= 0.7     && <0.12,
-                     vector-algorithms    >= 0.5     && <0.6
+                     vector               >= 0.7     && <0.13,
+                     vector-algorithms    >= 0.5     && <0.8
 
   if flag(chart)
     Build-depends:   Chart             == 0.14.*,
diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,10 @@
 # Hashtables changelog
 
+## 1.2.2.1
+
+  - Adjusted base lower bound (it was incorrect), bumped some testsuite +
+    benchmark bounds.
+
 ## 1.2.2.0
   - Bumped vector bounds.
 
diff --git a/hashtables.cabal b/hashtables.cabal
--- a/hashtables.cabal
+++ b/hashtables.cabal
@@ -1,5 +1,5 @@
 Name:                hashtables
-Version:             1.2.2.0
+Version:             1.2.2.1
 Synopsis:            Mutable hash tables in the ST monad
 Homepage:            http://github.com/gregorycollins/hashtables
 License:             BSD3
@@ -172,7 +172,7 @@
                      Data.HashTable.Internal.Utils,
                      Data.HashTable.Internal.Linear.Bucket
 
-  Build-depends:     base      >= 4   && <5,
+  Build-depends:     base      >= 4.7 && <5,
                      hashable  >= 1.1 && <1.2 || >= 1.2.1 && <1.3,
                      primitive,
                      vector    >= 0.7 && <0.13
diff --git a/src/Data/HashTable/Class.hs b/src/Data/HashTable/Class.hs
--- a/src/Data/HashTable/Class.hs
+++ b/src/Data/HashTable/Class.hs
@@ -48,6 +48,7 @@
 
 import           Control.Monad.ST
 import           Data.Hashable
+import           Data.Word        (Word)
 import           Prelude          hiding (mapM_)
 
 -- | A typeclass for hash tables in the 'ST' monad. The operations on these
diff --git a/test/hashtables-test.cabal b/test/hashtables-test.cabal
--- a/test/hashtables-test.cabal
+++ b/test/hashtables-test.cabal
@@ -126,7 +126,7 @@
                      test-framework             >= 0.3.1   && <0.9,
                      test-framework-quickcheck2 >= 0.2.6   && <0.4,
                      test-framework-hunit       >= 0.2.6   && <3,
-                     statistics                 >= 0.8     && <0.14,
+                     statistics                 >= 0.14    && <0.15,
                      primitive,
                      vector                     >= 0.7