diff --git a/Tests/Hasher.SHA1/HasherTests.cs b/Tests/Hasher.SHA1/HasherTests.cs
index 421adbd..4ce6781 100644
--- a/Tests/Hasher.SHA1/HasherTests.cs
+++ b/Tests/Hasher.SHA1/HasherTests.cs
@@ -8,10 +8,12 @@
 
     public static class HasherTests
     {
-        private const int MegabytesPerSecond = 500;
+        private const int MegabytesPerSecondLowSpeed = 200;
+        private const int MegabytesPerSecondHighSpeed = 1000;
 
         // Test vectors taken from http://csrc.nist.gov/groups/ST/toolkit/documents/Examples/SHA_All.pdf
         [Theory]
+        [InlineData("DA39A3EE 5E6B4B0D 3255BFEF 95601890 AFD80709", "")]
         [InlineData("A9993E36 4706816A BA3E2571 7850C26C 9CD0D89D", "abc")]
         [InlineData("84983E44 1C3BD26E BAAE4AA1 F95129E5 E54670F1", "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq")]
         public static async Task TestHashes(string expectedHash, string inputMessage)
@@ -25,13 +27,14 @@
 
         // Single-threaded SHA1 performance on i5-6500 is around 500MB/s
         [Theory]
-        [InlineData(1, 0, 1)]
-        [InlineData(1000, 0, 1)]
-        [InlineData(1000000, 0.5 * 1000 / MegabytesPerSecond, 2 * 1000 / MegabytesPerSecond)]
-        [InlineData(10000000, 0.5 * 10000 / MegabytesPerSecond, 2 * 10000 / MegabytesPerSecond)]
-        [InlineData(100000000, 0.5 * 100000 / MegabytesPerSecond, 2 * 100000 / MegabytesPerSecond)]
-        [InlineData(1000000000, 0.5 * 1000000 / MegabytesPerSecond, 2 * 1000000 / MegabytesPerSecond)]
-        public static async Task TestPerformance(int length, int minMilliseconds, int maxMilliseconds)
+        [InlineData(0)]
+        [InlineData(1)]
+        [InlineData(1000)]
+        [InlineData(1000000)]
+        [InlineData(10000000)]
+        [InlineData(100000000)]
+        [InlineData(1000000000)]
+        public static async Task TestPerformance(int length)
         {
             var messageBytes = new byte[length];
             for (var i = 0; i < length; i++)
@@ -39,13 +42,16 @@
                 messageBytes[i] = (byte)((int)(Math.E * length + Math.PI * i) % 256);
             }
 
+            var expectedTimeLow = length / (MegabytesPerSecondHighSpeed * 1000);
+            var expectedTimeHigh = 1 + length / (MegabytesPerSecondLowSpeed * 1000);
+
             var hasher = new SHA1ContentHasher();
             var stopwatch = new Stopwatch();
             stopwatch.Start();
             await hasher.ComputeHash(messageBytes);
             stopwatch.Stop();
 
-            Assert.InRange(stopwatch.ElapsedMilliseconds, minMilliseconds, maxMilliseconds);
+            Assert.InRange(stopwatch.ElapsedMilliseconds, expectedTimeLow, expectedTimeHigh);
         }
     }
 }