diff --git a/tests/xxhash/t_xxhash.ml b/tests/xxhash/t_xxhash.ml
index 81692294..6734b2b6 100644
--- a/tests/xxhash/t_xxhash.ml
+++ b/tests/xxhash/t_xxhash.ml
@@ -1,128 +1,111 @@
 include (val Containers_testlib.make ~__FILE__ ())
 module H = Containers_xxhash
 
-(* Gold tests: hash_string with seed=0 *)
+(* Gold tests: hash_string *)
 ;;
 
 t @@ fun () ->
-assert_equal ~printer:Int64.to_string (-1205034819632174695L)
-  (H.hash_string "" 0L);
+assert_equal ~printer:Int64.to_string (-1205034819632174695L) (H.hash_string "");
 assert_equal ~printer:Int64.to_string (-7444071767201028348L)
-  (H.hash_string "" 42L);
+  (H.hash_string_seed "" 42L);
 assert_equal ~printer:Int64.to_string 2794345569481354659L
-  (H.hash_string "hello" 0L);
+  (H.hash_string "hello");
 assert_equal ~printer:Int64.to_string (-4367754540140381902L)
-  (H.hash_string "hello" 42L);
+  (H.hash_string_seed "hello" 42L);
 assert_equal ~printer:Int64.to_string 1513236774081638803L
-  (H.hash_string "the quick brown fox" 0L);
+  (H.hash_string "the quick brown fox");
 assert_equal ~printer:Int64.to_string 6882318601984224800L
-  (H.hash_string "the quick brown fox" 42L);
+  (H.hash_string_seed "the quick brown fox" 42L);
 true
 ;;
 
-(* Gold tests: hash_int64 with seed=0 *)
+(* Gold tests: hash_int64 *)
 t @@ fun () ->
-assert_equal ~printer:Int64.to_string 3803688792395291579L (H.hash_int64 0L 0L);
-assert_equal ~printer:Int64.to_string (-6977822845260490347L)
-  (H.hash_int64 1L 0L);
+assert_equal ~printer:Int64.to_string 3803688792395291579L (H.hash_int64 0L);
+assert_equal ~printer:Int64.to_string (-6977822845260490347L) (H.hash_int64 1L);
 assert_equal ~printer:Int64.to_string (-8804195676797548855L)
-  (H.hash_int64 (-1L) 0L);
+  (H.hash_int64 (-1L));
 assert_equal ~printer:Int64.to_string (-7296932117151183542L)
-  (H.hash_int64 1234567890123456789L 0L);
+  (H.hash_int64 1234567890123456789L);
 true
 ;;
 
-(* Gold tests: hash_int32 with seed=0 *)
+(* Gold tests: hash_int32 *)
 t @@ fun () ->
-assert_equal ~printer:Int64.to_string 4246796580750024372L (H.hash_int32 0l 0L);
-assert_equal ~printer:Int64.to_string (-851299076295404719L)
-  (H.hash_int32 1l 0L);
-assert_equal ~printer:Int64.to_string 9185342943168159635L
-  (H.hash_int32 (-1l) 0L);
-assert_equal ~printer:Int64.to_string (-2929917330072466447L)
-  (H.hash_int32 42l 0L);
+assert_equal ~printer:Int64.to_string 4246796580750024372L (H.hash_int32 0l);
+assert_equal ~printer:Int64.to_string (-851299076295404719L) (H.hash_int32 1l);
+assert_equal ~printer:Int64.to_string 9185342943168159635L (H.hash_int32 (-1l));
+assert_equal ~printer:Int64.to_string (-2929917330072466447L) (H.hash_int32 42l);
 true
 ;;
 
-(* Gold tests: hash_int with seed=0 *)
+(* Gold tests: hash_int *)
 t @@ fun () ->
-assert_equal ~printer:Int64.to_string 3803688792395291579L (H.hash_int 0 0L);
-assert_equal ~printer:Int64.to_string (-6977822845260490347L) (H.hash_int 1 0L);
-assert_equal ~printer:Int64.to_string (-8804195676797548855L)
-  (H.hash_int (-1) 0L);
-assert_equal ~printer:Int64.to_string (-5379971487550586029L) (H.hash_int 42 0L);
+assert_equal ~printer:Int64.to_string 3803688792395291579L (H.hash_int 0);
+assert_equal ~printer:Int64.to_string (-6977822845260490347L) (H.hash_int 1);
+assert_equal ~printer:Int64.to_string (-8804195676797548855L) (H.hash_int (-1));
+assert_equal ~printer:Int64.to_string (-5379971487550586029L) (H.hash_int 42);
 true
 ;;
 
 (* Gold tests: hash_bool *)
 t @@ fun () ->
-assert_equal ~printer:Int64.to_string 3803688792395291579L
-  (H.hash_bool false 0L);
-assert_equal ~printer:Int64.to_string (-6977822845260490347L)
-  (H.hash_bool true 0L);
+assert_equal ~printer:Int64.to_string 3803688792395291579L (H.hash_bool false);
+assert_equal ~printer:Int64.to_string (-6977822845260490347L) (H.hash_bool true);
 true
 ;;
 
 (* Gold tests: hash_char *)
 t @@ fun () ->
-(* 'a' = 97 *)
-assert_equal ~printer:Int64.to_string (H.hash_int 97 0L) (H.hash_char 'a' 0L);
-(* '0' = 48 *)
-assert_equal ~printer:Int64.to_string (H.hash_int 48 0L) (H.hash_char '0' 0L);
+(* 'a' = 97, '0' = 48 *)
+assert_equal ~printer:Int64.to_string (H.hash_int 97) (H.hash_char 'a');
+assert_equal ~printer:Int64.to_string (H.hash_int 48) (H.hash_char '0');
 true
 ;;
 
 (* Property tests: determinism *)
 q ~count:10_000 Q.string @@ fun s ->
-Int64.equal (H.hash_string s 0L) (H.hash_string s 0L)
+Int64.equal (H.hash_string s) (H.hash_string s)
 ;;
 
 q ~count:10_000 Q.int64 @@ fun v ->
-Int64.equal (H.hash_int64 v 0L) (H.hash_int64 v 0L)
+Int64.equal (H.hash_int64 v) (H.hash_int64 v)
 ;;
 
-q ~count:10_000 Q.int @@ fun v ->
-Int64.equal (H.hash_int v 0L) (H.hash_int v 0L)
-;;
+q ~count:10_000 Q.int @@ fun v -> Int64.equal (H.hash_int v) (H.hash_int v);;
+q ~count:10_000 Q.bool @@ fun b -> Int64.equal (H.hash_bool b) (H.hash_bool b);;
+q ~count:10_000 Q.char @@ fun c -> Int64.equal (H.hash_char c) (H.hash_char c);;
 
-q ~count:10_000 Q.bool @@ fun b ->
-Int64.equal (H.hash_bool b 0L) (H.hash_bool b 0L)
-;;
-
-q ~count:10_000 Q.char @@ fun c ->
-Int64.equal (H.hash_char c 0L) (H.hash_char c 0L)
-;;
-
-(* Different seeds give different results for the same input (seed nonzero) *)
+(* Different seeds give different results for the same input *)
 q ~count:10_000 (Q.pair Q.string Q.int64) @@ fun (s, seed) ->
 Q.assume (not (Int64.equal seed 0L));
-not (Int64.equal (H.hash_string s 0L) (H.hash_string s seed))
+not (Int64.equal (H.hash_string s) (H.hash_string_seed s seed))
 ;;
 
 q ~count:10_000 (Q.pair Q.int64 Q.int64) @@ fun (v, seed) ->
 Q.assume (not (Int64.equal seed 0L));
-not (Int64.equal (H.hash_int64 v 0L) (H.hash_int64 v seed))
+not (Int64.equal (H.hash_int64 v) (H.hash_int64_seed v seed))
 ;;
 
 q ~count:10_000 (Q.pair Q.int Q.int64) @@ fun (v, seed) ->
 Q.assume (not (Int64.equal seed 0L));
-not (Int64.equal (H.hash_int v 0L) (H.hash_int v seed))
+not (Int64.equal (H.hash_int v) (H.hash_int_seed v seed))
 ;;
 
 (* Different inputs give different results for the same seed *)
 q ~count:10_000 (Q.pair Q.string Q.string) @@ fun (s1, s2) ->
 Q.assume (not (String.equal s1 s2));
-not (Int64.equal (H.hash_string s1 0L) (H.hash_string s2 0L))
+not (Int64.equal (H.hash_string s1) (H.hash_string s2))
 ;;
 
 q ~count:10_000 (Q.pair Q.int64 Q.int64) @@ fun (a, b) ->
 Q.assume (not (Int64.equal a b));
-not (Int64.equal (H.hash_int64 a 0L) (H.hash_int64 b 0L))
+not (Int64.equal (H.hash_int64 a) (H.hash_int64 b))
 ;;
 
 q ~count:10_000 (Q.pair Q.int Q.int) @@ fun (a, b) ->
 Q.assume (a <> b);
-not (Int64.equal (H.hash_int a 0L) (H.hash_int b 0L))
+not (Int64.equal (H.hash_int a) (H.hash_int b))
 ;;
 
 (* Stress test: hash 100k strings of varying lengths, non-empty => non-zero *)
@@ -130,7 +113,7 @@ t @@ fun () ->
 for len = 0 to 99 do
   for _ = 1 to 1000 do
     let s = String.make len 'x' in
-    let h = H.hash_string s 0L in
+    let h = H.hash_string s in
     if len > 0 then
       if Int64.equal h 0L then
         failwith