diff --git a/src/Microsoft.AspNet.Server.Kestrel/Infrastructure/LongExtensions.cs b/src/Microsoft.AspNet.Server.Kestrel/Infrastructure/LongExtensions.cs
index 0ac6a718d4..3b79425172 100644
--- a/src/Microsoft.AspNet.Server.Kestrel/Infrastructure/LongExtensions.cs
+++ b/src/Microsoft.AspNet.Server.Kestrel/Infrastructure/LongExtensions.cs
@@ -7,12 +7,18 @@ namespace Microsoft.AspNet.Server.Kestrel.Extensions
     {
         public static int BitCount(this long value)
         {
-            // Parallel bit count for a 64-bit integer
+            // see https://github.com/dotnet/corefx/blob/master/src/System.Reflection.Metadata/src/System/Reflection/Internal/Utilities/BitArithmetic.cs
+
+            const ulong Mask01010101 = 0x5555555555555555UL;
+            const ulong Mask00110011 = 0x3333333333333333UL;
+            const ulong Mask00001111 = 0x0F0F0F0F0F0F0F0FUL;
+            const ulong Mask00000001 = 0x0101010101010101UL;
+
             var v = (ulong)value;
-            v = v - ((v >> 1) & 0x5555555555555555);
-            v = (v & 0x3333333333333333) + ((v >> 2) & 0x3333333333333333);
-            v = (v + (v >> 4) & 0x0f0f0f0f0f0f0f0f);
-            return (int)((v * 0x0101010101010101) >> 56);
+
+            v = v - ((v >> 1) & Mask01010101);
+            v = (v & Mask00110011) + ((v >> 2) & Mask00110011);
+            return (int)(unchecked(((v + (v >> 4)) & Mask00001111) * Mask00000001) >> 56);
         }
     }
 }