diff --git a/src/semaphore/dune b/src/semaphore/dune
index 384c9f633..a714e8be5 100644
--- a/src/semaphore/dune
+++ b/src/semaphore/dune
@@ -1,8 +1,16 @@
 ;; Tests of Semaphore.Counting
+(test
+ (name stm_tests_counting)
+ (modules stm_tests_counting)
+ (package multicoretests)
+ (libraries qcheck-stm.sequential qcheck-stm.domain)
+ (action (run %{test} --verbose))
+)
 
+;; Tests of Semaphore.Binary
 (test
- (name stm_tests)
- (modules stm_tests)
+ (name stm_tests_binary)
+ (modules stm_tests_binary)
  (package multicoretests)
  (libraries qcheck-stm.sequential qcheck-stm.domain)
  (action (run %{test} --verbose))
diff --git a/src/semaphore/stm_tests_binary.ml b/src/semaphore/stm_tests_binary.ml
new file mode 100644
index 000000000..a4a45e499
--- /dev/null
+++ b/src/semaphore/stm_tests_binary.ml
@@ -0,0 +1,74 @@
+open QCheck
+open STM
+
+(** parallel STM tests of Semaphore.Binary *)
+
+(* Semaphore API these tests will exercise
+
+  val make : bool -> t
+  val release : t -> unit
+  val acquire : t -> unit
+  val try_acquire : t -> bool
+
+*)
+
+module SBConf =
+  struct
+    type sut = Semaphore.Binary.t
+    type state = int
+
+    type cmd =
+      | Release
+      | Acquire
+      | TryAcquire
+
+    let pp_cmd _ fmt x =
+      let open Util.Pp in
+      match x with
+      | Release -> cst0 "Release" fmt
+      | Acquire -> cst0 "Acquire" fmt
+      | TryAcquire -> cst0 "TryAcquire" fmt
+
+    let show_cmd = Util.Pp.to_show pp_cmd
+
+    let init_state = 1
+    let init_sut () = Semaphore.Binary.make true
+    let cleanup _ = ()
+
+    let arb_cmd s =
+      let cmds = [ Release; TryAcquire; ] in
+      let cmds = if s = 1 then Acquire :: cmds else cmds in
+      QCheck.make ~print:show_cmd (Gen.oneofl cmds)
+
+    let next_state c s = match c with
+      | Release -> 1
+      | Acquire -> 0
+      | TryAcquire -> if s = 1 then 0 else 0
+
+    let run c sem =
+      match c with
+      | Release    -> Res (unit, Semaphore.Binary.release sem)
+      | Acquire    -> Res (unit, Semaphore.Binary.acquire sem)
+      | TryAcquire -> Res (bool, Semaphore.Binary.try_acquire sem)
+
+    let precond c s =
+      match c with
+      | Acquire -> s = 1
+      | _       -> true
+    let postcond c s res =
+      match c,res with
+      | Release,    Res ((Unit,_), _)
+      | Acquire,    Res ((Unit,_), _) -> true
+      | TryAcquire, Res ((Bool,_),r)  -> r = (s = 1)
+      | _                             -> false
+  end
+
+module SBTest_seq = STM_sequential.Make(SBConf)
+module SBTest_dom = STM_domain.Make(SBConf)
+
+let _ =
+  QCheck_base_runner.run_tests_main
+    (let count = 500 in
+     [SBTest_seq.agree_test     ~count ~name:"STM Semaphore.Binary test sequential";
+      SBTest_dom.agree_test_par ~count ~name:"STM Semaphore.Binary test parallel";
+     ])
diff --git a/src/semaphore/stm_tests.ml b/src/semaphore/stm_tests_counting.ml
similarity index 75%
rename from src/semaphore/stm_tests.ml
rename to src/semaphore/stm_tests_counting.ml
index c00a0acfd..efee0356e 100644
--- a/src/semaphore/stm_tests.ml
+++ b/src/semaphore/stm_tests_counting.ml
@@ -73,11 +73,19 @@ module SCConf =
   end
 
 module SCTest_seq = STM_sequential.Make(SCConf)
-module SCTest_dom = STM_domain.Make(SCConf)
+module SCTest_dom_gv = STM_domain.Make(SCConf)
+module SCTest_dom = STM_domain.Make(struct
+    include SCConf
+    let arb_cmd s =
+      let cmds = [ Release; TryAcquire; ] in (* No GetValue *)
+      let cmds = if s > 0 then Acquire :: cmds else cmds in
+      QCheck.make ~print:show_cmd (Gen.oneofl cmds)
+  end)
 
 let _ =
   QCheck_base_runner.run_tests_main
     (let count = 200 in
-     [SCTest_seq.agree_test     ~count ~name:"STM Semaphore.Counting test sequential";
-      SCTest_dom.agree_test_par ~count ~name:"STM Semaphore.Counting test parallel";
+     [SCTest_seq.agree_test        ~count ~name:"STM Semaphore.Counting test sequential";
+      SCTest_dom_gv.agree_test_par ~count ~name:"STM Semaphore.Counting test parallel (w/ get_value)";
+      SCTest_dom.agree_test_par    ~count ~name:"STM Semaphore.Counting test parallel (w/o get_value)";
      ])