diff --git a/X10D/src/Math/Int64Extensions.cs b/X10D/src/Math/Int64Extensions.cs
index 94fb8d7cd..8d76498a0 100644
--- a/X10D/src/Math/Int64Extensions.cs
+++ b/X10D/src/Math/Int64Extensions.cs
@@ -148,11 +148,6 @@ public static bool IsPrime(this long value)
             return false;
         }
 
-        if ((value + 1) % 6 != 0 && (value - 1) % 6 != 0)
-        {
-            return false;
-        }
-
         for (var iterator = 5L; iterator * iterator <= value; iterator += 6)
         {
             if (value % iterator == 0 || value % (iterator + 2) == 0)
diff --git a/X10D/src/Math/UInt64Extensions.cs b/X10D/src/Math/UInt64Extensions.cs
index ca5c2f518..818a97501 100644
--- a/X10D/src/Math/UInt64Extensions.cs
+++ b/X10D/src/Math/UInt64Extensions.cs
@@ -125,11 +125,6 @@ public static bool IsPrime(this ulong value)
             return false;
         }
 
-        if ((value + 1) % 6 != 0 && (value - 1) % 6 != 0)
-        {
-            return false;
-        }
-
         for (var iterator = 5UL; iterator * iterator <= value; iterator += 6)
         {
             if (value % iterator == 0 || value % (iterator + 2) == 0)