diff --git a/ascii-string.cabal b/ascii-string.cabal
--- a/ascii-string.cabal
+++ b/ascii-string.cabal
@@ -1,7 +1,7 @@
 name:
   ascii-string
 version:
-  1.0.0.1
+  1.0.1
 synopsis:
   Compact representation of ASCII strings
 description:
@@ -42,6 +42,7 @@
     base >=4.7 && <5,
     bytestring >=0.10 && <0.11,
     cereal >=0.5.5 && <0.6,
+    deepseq >=1.4 && <2,
     deferred-folds >=0.6.11 && <0.7,
     foldl >=1.4 && <2,
     hashable >=1.2.7 && <2,
diff --git a/library/AsciiString.hs b/library/AsciiString.hs
--- a/library/AsciiString.hs
+++ b/library/AsciiString.hs
@@ -31,6 +31,9 @@
 deriving instance Ord AsciiString
 deriving instance Generic AsciiString
 
+instance NFData AsciiString where
+  rnf a = seq a ()
+
 instance Hashable AsciiString where
   hashWithSalt salt (AsciiString size pa@(PrimArray ba)) =
     hashByteArrayWithSalt ba 0 (sizeofPrimArray pa) (hashWithSalt salt size)
diff --git a/library/AsciiString/Prelude.hs b/library/AsciiString/Prelude.hs
--- a/library/AsciiString/Prelude.hs
+++ b/library/AsciiString/Prelude.hs
@@ -98,6 +98,10 @@
 -------------------------
 import Data.Hashable as Exports
 
+-- deepseq
+-------------------------
+import Control.DeepSeq as Exports
+
 
 data Product2 a b = Product2 !a !b