diff --git a/changelog b/changelog
--- a/changelog
+++ b/changelog
@@ -1,3 +1,6 @@
+0.3.5.1
+	* Replace use of Vector from vector with Array from primitive.
+
 0.3.5.0
 	* Export scientificP :: ReadP Scientific
 	  (Courtesy of Shlok Datye @shlok)
diff --git a/scientific.cabal b/scientific.cabal
--- a/scientific.cabal
+++ b/scientific.cabal
@@ -1,5 +1,5 @@
 name:                scientific
-version:             0.3.5.0
+version:             0.3.5.1
 synopsis:            Numbers represented using scientific notation
 description:
   @Data.Scientific@ provides the number type 'Scientific'. Scientific numbers are
@@ -72,7 +72,7 @@
                      , deepseq     >= 1.3   && < 1.5
                      , text        >= 0.8   && < 1.3
                      , hashable    >= 1.1.2 && < 1.3
-                     , vector      >= 0.7   && < 0.13
+                     , primitive   >= 0.1   && < 0.7
                      , containers  >= 0.1   && < 0.6
                      , binary      >= 0.4.1 && < 0.9
 
@@ -104,7 +104,7 @@
                , tasty-ant-xml    >= 1.0   && < 1.2
                , tasty-hunit      >= 0.8   && < 0.10
                , tasty-smallcheck >= 0.2   && < 0.9
-               , tasty-quickcheck >= 0.8   && < 0.9
+               , tasty-quickcheck >= 0.8   && < 0.10
                , smallcheck       >= 1.0   && < 1.2
                , QuickCheck       >= 2.5   && < 2.11
                , text             >= 0.8   && < 1.3
diff --git a/src/Data/Scientific.hs b/src/Data/Scientific.hs
--- a/src/Data/Scientific.hs
+++ b/src/Data/Scientific.hs
@@ -105,8 +105,7 @@
 import qualified Data.Map            as M     (Map, empty, insert, lookup)
 import           Data.Ratio                   ((%), numerator, denominator)
 import           Data.Typeable                (Typeable)
-import qualified Data.Vector         as V
-import qualified Data.Vector.Mutable as VM
+import qualified Data.Primitive.Array as Primitive
 import           Data.Word                    (Word8, Word16, Word32, Word64)
 import           Math.NumberTheory.Logarithms (integerLog10')
 import qualified Numeric                      (floatToDigits)
@@ -579,20 +578,20 @@
 maxExpt :: Int
 maxExpt = 324
 
-expts10 :: V.Vector Integer
+expts10 :: Primitive.Array Integer
 expts10 = runST $ do
-    mv <- VM.unsafeNew maxExpt
-    VM.unsafeWrite mv 0  1
-    VM.unsafeWrite mv 1 10
+    ma <- Primitive.newArray maxExpt uninitialised
+    Primitive.writeArray ma 0  1
+    Primitive.writeArray ma 1 10
     let go !ix
-          | ix == maxExpt = V.unsafeFreeze mv
+          | ix == maxExpt = Primitive.unsafeFreezeArray ma
           | otherwise = do
-              VM.unsafeWrite mv  ix        xx
-              VM.unsafeWrite mv (ix+1) (10*xx)
+              Primitive.writeArray ma  ix        xx
+              Primitive.writeArray ma (ix+1) (10*xx)
               go (ix+2)
           where
             xx = x * x
-            x  = V.unsafeIndex expts10 half
+            x  = Primitive.indexArray expts10 half
 #if MIN_VERSION_base(4,5,0)
             !half = ix `unsafeShiftR` 1
 #else
@@ -600,12 +599,15 @@
 #endif
     go 2
 
+uninitialised :: error
+uninitialised = error "Data.Scientific: uninitialised element"
+
 -- | @magnitude e == 10 ^ e@
 magnitude :: Int -> Integer
 magnitude e | e < maxExpt = cachedPow10 e
             | otherwise   = cachedPow10 hi * 10 ^ (e - hi)
     where
-      cachedPow10 = V.unsafeIndex expts10
+      cachedPow10 = Primitive.indexArray expts10
 
       hi = maxExpt - 1