diff --git a/test/Test/Sampler.hs b/test/Test/Sampler.hs
index cdc3bb7..6d61ce1 100644
--- a/test/Test/Sampler.hs
+++ b/test/Test/Sampler.hs
@@ -51,16 +51,28 @@ tests =
         (obsSize, obsAbs) <- runLambdaSampler 1_000
         close obsSize 10_000 0.2 -- just to be sure
         close obsAbs 4_000 0.2 -- just to be sure
+    , testCase "Binary lambda sampler has the correct output distribution" $ do
+        (obsSize, obsAbs) <- runBinLambdaSampler 1_000
+        close obsSize 6_000 0.2 -- just to be sure
+        close obsAbs 2_340 0.2 -- just to be sure
     ]
 
 lambdaSampler :: BuffonMachine SMGen Lambda
 lambdaSampler = rejectionSampler (MkLowerBound 8_000) (MkUpperBound 12_000)
 
+binLambdaSampler :: BuffonMachine SMGen Lambda
+binLambdaSampler = rejectionSampler (MkLowerBound 5_000) (MkUpperBound 6_400)
+
 runLambdaSampler :: Int -> IO (Double, Double)
 runLambdaSampler n = evalIO $ do
   sam <- replicateM n lambdaSampler
   pure $ statistics $ (\t -> (size t, abstractions t)) <$> sam
 
+runBinLambdaSampler :: Int -> IO (Double, Double)
+runBinLambdaSampler n = evalIO $ do
+  sam <- replicateM n binLambdaSampler
+  pure $ statistics $ (\t -> (size t, abstractions t)) <$> sam
+
 statistics :: [(Int, Int)] -> (Double, Double)
 statistics xs = (average $ fst <$> xs, average $ snd <$> xs)
 
diff --git a/test/Test/Samplers/Lambda.hs b/test/Test/Samplers/Lambda.hs
index dece87a..b1bc88d 100644
--- a/test/Test/Samplers/Lambda.hs
+++ b/test/Test/Samplers/Lambda.hs
@@ -85,7 +85,7 @@ mkBoltzmannSampler
   System
     { targetType = ''BinLambda
     , meanSize = 6_000
-    , frequencies = def
+    , frequencies = ('Abs, 2340) <:> def
     , weights =
         ('Index, 0)
           <:> ('App, 2)