diff --git a/AsyncKeyedLock.Tests/AsyncKeyedLock.Tests.csproj b/AsyncKeyedLock.Tests/AsyncKeyedLock.Tests.csproj
index 4515249..eb5397e 100644
--- a/AsyncKeyedLock.Tests/AsyncKeyedLock.Tests.csproj
+++ b/AsyncKeyedLock.Tests/AsyncKeyedLock.Tests.csproj
@@ -6,6 +6,10 @@
     <Nullable>enable</Nullable>
 
     <IsPackable>false</IsPackable>
+
+    <SignAssembly>True</SignAssembly>
+
+    <AssemblyOriginatorKeyFile>AsyncKeyedLock.Tests.snk</AssemblyOriginatorKeyFile>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/AsyncKeyedLock.Tests/AsyncKeyedLock.Tests.snk b/AsyncKeyedLock.Tests/AsyncKeyedLock.Tests.snk
new file mode 100644
index 0000000..3a9c925
Binary files /dev/null and b/AsyncKeyedLock.Tests/AsyncKeyedLock.Tests.snk differ
diff --git a/AsyncKeyedLock.Tests/StripedAsyncKeyedLocker/OriginalTests.cs b/AsyncKeyedLock.Tests/StripedAsyncKeyedLocker/OriginalTests.cs
index 3a7353d..c4c6cac 100644
--- a/AsyncKeyedLock.Tests/StripedAsyncKeyedLocker/OriginalTests.cs
+++ b/AsyncKeyedLock.Tests/StripedAsyncKeyedLocker/OriginalTests.cs
@@ -1,6 +1,7 @@
 using AsyncKeyedLock.Tests.Helpers;
 using FluentAssertions;
 using ListShuffle;
+using System.Collections;
 using System.Collections.Concurrent;
 using Xunit;
 
@@ -8,6 +9,62 @@ namespace AsyncKeyedLock.Tests.StripedAsyncKeyedLocker
 {
     public class OriginalTests
     {
+        [Fact]
+        public void TestHashHelpersIsPrime0DoesNotThrow()
+        {
+            Action action = () =>
+            {
+                var asyncKeyedLocker = new StripedAsyncKeyedLocker<string>(0);
+            };
+            action.Should().NotThrow();
+        }
+
+        [Fact]
+        public void TestHashHelpersIsPrime1DoesNotThrow()
+        {
+            Action action = () =>
+            {
+                var asyncKeyedLocker = new StripedAsyncKeyedLocker<string>(1);
+            };
+            action.Should().NotThrow();
+        }
+
+        [Fact]
+        public void TestHashHelpersIsPrime7199370DoesNotThrow()
+        {
+            Action action = () =>
+            {
+                var asyncKeyedLocker = new StripedAsyncKeyedLocker<string>(7199370);
+            };
+            action.Should().NotThrow();
+        }
+
+        [Fact]
+        public void TestHashHelpersIsPrime7199371DoesNotThrow()
+        {
+            Action action = () =>
+            {
+                var asyncKeyedLocker = new StripedAsyncKeyedLocker<string>(7199372);
+            };
+            action.Should().NotThrow();
+        }
+
+        [Fact]
+        public void TestHashHelpersIsPrimeNegative1ThrowsArgumentException()
+        {
+            Action action = () =>
+            {
+                var asyncKeyedLocker = new StripedAsyncKeyedLocker<string>(-1);
+            };
+            action.Should().Throw<ArgumentException>();
+        }
+
+        [Fact]
+        public void TestHashHelpersIsPrime2()
+        {
+            HashHelpers.IsPrime(2).Should().Be(true);
+        }
+
         [Fact]
         public async Task TestTimeout()
         {
diff --git a/AsyncKeyedLock/HashHelpers.cs b/AsyncKeyedLock/HashHelpers.cs
index c360bb5..d1d965c 100644
--- a/AsyncKeyedLock/HashHelpers.cs
+++ b/AsyncKeyedLock/HashHelpers.cs
@@ -1,11 +1,8 @@
-// This code is taken directly from Microsoft's source code with minor alterations. Credit belongs to Microsoft.
+// This code is taken directly from Microsoft's source code with some alterations. Credit belongs to Microsoft.
 
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using System.Diagnostics;
-using System.Runtime.CompilerServices;
-
 namespace System.Collections
 {
     internal static partial class HashHelpers
@@ -84,43 +81,5 @@ public static int GetPrime(int min)
             }
             return min;
         }
-
-        // Returns size of hashtable to grow to.
-        public static int ExpandPrime(int oldSize)
-        {
-            int newSize = 2 * oldSize;
-
-            // Allow the hashtables to grow to maximum possible size (~2G elements) before encountering capacity overflow.
-            // Note that this check works even when _items.Length overflowed thanks to the (uint) cast
-            if ((uint)newSize > MaxPrimeArrayLength && MaxPrimeArrayLength > oldSize)
-            {
-                Debug.Assert(MaxPrimeArrayLength == GetPrime(MaxPrimeArrayLength), "Invalid MaxPrimeArrayLength");
-                return MaxPrimeArrayLength;
-            }
-
-            return GetPrime(newSize);
-        }
-
-        /// <summary>Returns approximate reciprocal of the divisor: ceil(2**64 / divisor).</summary>
-        /// <remarks>This should only be used on 64-bit.</remarks>
-        public static ulong GetFastModMultiplier(uint divisor) =>
-            ulong.MaxValue / divisor + 1;
-
-        /// <summary>Performs a mod operation using the multiplier pre-computed with <see cref="GetFastModMultiplier"/>.</summary>
-        /// <remarks>This should only be used on 64-bit.</remarks>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static uint FastMod(uint value, uint divisor, ulong multiplier)
-        {
-            // We use modified Daniel Lemire's fastmod algorithm (https://github.com/dotnet/runtime/pull/406),
-            // which allows to avoid the long multiplication if the divisor is less than 2**31.
-            Debug.Assert(divisor <= int.MaxValue);
-
-            // This is equivalent of (uint)Math.BigMul(multiplier * value, divisor, out _). This version
-            // is faster than BigMul currently because we only need the high bits.
-            uint highbits = (uint)(((((multiplier * value) >> 32) + 1) * divisor) >> 32);
-
-            Debug.Assert(highbits == value % divisor);
-            return highbits;
-        }
     }
 }
\ No newline at end of file
diff --git a/AsyncKeyedLock/StripedAsyncKeyedLocker.cs b/AsyncKeyedLock/StripedAsyncKeyedLocker.cs
index 6af137e..ae273f2 100644
--- a/AsyncKeyedLock/StripedAsyncKeyedLocker.cs
+++ b/AsyncKeyedLock/StripedAsyncKeyedLocker.cs
@@ -5,6 +5,10 @@
 using System.Threading;
 using System.Threading.Tasks;
 
+[assembly: InternalsVisibleTo("AsyncKeyedLock.Tests, PublicKey=002400000480000094000000060200000024000052534131000" +
+    "4000001000100a5cffbe51901ba498a225214c7eee4ff5f0341aad9f7605a596e72dbffdf234bcf2c157f7e3a4e2a3900cbc0d3919a6b" +
+    "938cdf09e2aa5949fdd8f1dbda151853a00a08578724fb36f8c44112dadf388f75a5aab469f51a43b49f2e2fce355357291b01471606b" +
+    "0c071fd5fe1641f1c7b0165d16f365748a613671681938cf6c1")]
 namespace AsyncKeyedLock
 {
     /// <summary>
@@ -923,5 +927,10 @@ public bool IsInUse(TKey key)
         {
             return Get(key).SemaphoreSlim.CurrentCount < MaxCount;
         }
+
+        internal bool IsPrime(int candidate)
+        {
+            return HashHelpers.IsPrime(candidate);
+        }
     }
 }