diff --git a/FastRng/Double/ShapeFitter.cs b/FastRng/Double/ShapeFitter.cs
index a0c9c43..6fe2ff8 100644
--- a/FastRng/Double/ShapeFitter.cs
+++ b/FastRng/Double/ShapeFitter.cs
@@ -2,51 +2,55 @@ using System;
 using System.Runtime.CompilerServices;
 using System.Threading;
 using System.Threading.Tasks;
+using FastRng.Double.Distributions;
 
 namespace FastRng.Double
 {
+    /// <summary>
+    /// ShapeFitter is a rejection sampler, cf. https://en.wikipedia.org/wiki/Rejection_sampling
+    /// </summary>
     public sealed class ShapeFitter
     {
         private readonly double[] probabilities;
-        private readonly double[] samples;
         private readonly IRandom rng;
-        private readonly ushort sampleSize;
-        private readonly double threshold;
-        
-        public ShapeFitter(Func<double, double> shapeFunction, IRandom rng, ushort sampleSize = 50, double threshold = 0.99)
+        private readonly double max;
+        private readonly double sampleSize;
+        private readonly IDistribution uniform = new Uniform();
+
+        public ShapeFitter(Func<double, double> shapeFunction, IRandom rng, ushort sampleSize = 50)
         {
             this.rng = rng;
-            this.threshold = threshold;
             this.sampleSize = sampleSize;
-            this.samples = new double[sampleSize];
             this.probabilities = new double[sampleSize];
-            
-            var sampleStepSize = 1.0 / sampleSize;
+
+            var sampleStepSize = 1.0d / sampleSize;
             var nextStep = 0.0 + sampleStepSize;
+            var maxValue = 0.0d;
             for (var n = 0; n < sampleSize; n++)
             {
                 this.probabilities[n] = shapeFunction(nextStep);
+                if (this.probabilities[n] > maxValue)
+                    maxValue = this.probabilities[n];
+                
                 nextStep += sampleStepSize;
             }
+
+            this.max = maxValue;
         }
 
         public async ValueTask<double> NextNumber(CancellationToken token = default)
         {
             while (!token.IsCancellationRequested)
             {
-                var nextNumber = await this.rng.GetUniform(token);
-                var nextBucket = (int)Math.Floor(nextNumber * this.sampleSize);
-                // var firstInBucket = this.samples[nextBucket] == 0;
-                this.samples[nextBucket] += this.probabilities[nextBucket];
-
-                // if (firstInBucket) // TODO: Could be an option (optional)
-                //     return nextNumber;
+                var x = await this.rng.GetUniform(token);
+                var nextBucket = (int)Math.Floor(x * this.sampleSize);
+                var threshold = this.probabilities[nextBucket];
+                var y = await this.rng.NextNumber(0.0d, this.max, this.uniform, token);
                 
-                if (this.samples[nextBucket] >= this.threshold)
-                {
-                    this.samples[nextBucket] -= this.threshold;
-                    return nextNumber;
-                }
+                if(y > threshold)
+                    continue;
+
+                return x;
             }
 
             return double.NaN;