diff --git a/library/StrictList.hs b/library/StrictList.hs
--- a/library/StrictList.hs
+++ b/library/StrictList.hs
@@ -89,6 +89,10 @@
 
 instance Hashable a => Hashable (List a)
 
+instance NFData a => NFData (List a)
+
+instance NFData1 List
+
 {-|
 Reverse the list.
 -}
diff --git a/library/StrictList/Prelude.hs b/library/StrictList/Prelude.hs
--- a/library/StrictList/Prelude.hs
+++ b/library/StrictList/Prelude.hs
@@ -90,3 +90,7 @@
 -- hashable
 -------------------------
 import Data.Hashable as Exports (Hashable)
+
+-- deepseq
+-------------------------
+import Control.DeepSeq as Exports
diff --git a/strict-list.cabal b/strict-list.cabal
--- a/strict-list.cabal
+++ b/strict-list.cabal
@@ -1,5 +1,5 @@
 name: strict-list
-version: 0.1.5
+version: 0.1.6
 synopsis: Strict linked list
 description:
   Implementation of strict linked list with care taken about stack.
@@ -27,6 +27,7 @@
     StrictList.Prelude
   build-depends:
     base >=4.9 && <5,
+    deepseq >=1.4.3 && <1.5,
     hashable >=1.2 && <2,
     semigroupoids >=5.3 && <6