diff --git a/X10D.Tests/src/Core/BooleanTests.cs b/X10D.Tests/src/Core/BooleanTests.cs
index df2a850..7f01f63 100644
--- a/X10D.Tests/src/Core/BooleanTests.cs
+++ b/X10D.Tests/src/Core/BooleanTests.cs
@@ -1,4 +1,4 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
 
 namespace X10D.Tests.Core
 {
@@ -20,8 +20,11 @@ namespace X10D.Tests.Core
             var trueBytes = new byte[] { 0x01 };
             var falseBytes = new byte[] { 0x00 };
 
-            var trueResult = trueValue.GetBytes();
-            var falseResult = falseValue.GetBytes();
+            byte[] trueResult = trueValue.GetBytes();
+            byte[] falseResult = falseValue.GetBytes();
+            
+            Assert.AreEqual(1, trueResult.Length);
+            Assert.AreEqual(1, trueResult.Length);
 
             CollectionAssert.AreEqual(trueBytes, trueResult);
             CollectionAssert.AreEqual(falseBytes, falseResult);
diff --git a/X10D.Tests/src/Core/CharTests.cs b/X10D.Tests/src/Core/CharTests.cs
index e973ceb..c2a8360 100644
--- a/X10D.Tests/src/Core/CharTests.cs
+++ b/X10D.Tests/src/Core/CharTests.cs
@@ -15,7 +15,7 @@ namespace X10D.Tests.Core
             const int repeatCount = 10;
 
             const string repeated = "aaaaaaaaaa";
-            var result = character.Repeat(repeatCount);
+            string result = character.Repeat(repeatCount);
 
             Assert.AreEqual(repeated, result);
             Assert.ThrowsException<ArgumentOutOfRangeException>(() => character.Repeat(-1));
diff --git a/X10D.Tests/src/Core/IsPrimeTests.cs b/X10D.Tests/src/Core/IsPrimeTests.cs
index dfe4dab..cbba572 100644
--- a/X10D.Tests/src/Core/IsPrimeTests.cs
+++ b/X10D.Tests/src/Core/IsPrimeTests.cs
@@ -35,8 +35,8 @@ namespace X10D.Tests.Core
         {
             for (var index = 0; index < _primeNumbers.Count; index++)
             {
-                var value = _primeNumbers[index];
-                var result = value.IsPrime();
+                int value = _primeNumbers[index];
+                bool result = value.IsPrime();
                 Assert.IsTrue(result, value.ToString("N0", CultureInfo.InvariantCulture));
             }
         }
@@ -49,7 +49,7 @@ namespace X10D.Tests.Core
         {
             for (var value = short.MinValue; value < 0; value++)
             {
-                var result = value.IsPrime();
+                bool result = value.IsPrime();
                 Assert.IsFalse(result, value.ToString("N0", CultureInfo.InvariantCulture));
             }
         }
@@ -62,7 +62,7 @@ namespace X10D.Tests.Core
         {
             for (var value = 0; value < 2; value++)
             {
-                var result = value.IsPrime();
+                bool result = value.IsPrime();
                 Assert.IsFalse(result, value.ToString("N0", CultureInfo.InvariantCulture));
             }
         }
@@ -75,8 +75,8 @@ namespace X10D.Tests.Core
         {
             for (var value = 0; value < 7920; value++)
             {
-                var expected = _primeNumbers.Contains(value);
-                var actual = value.IsPrime();
+                bool expected = _primeNumbers.Contains(value);
+                bool actual = value.IsPrime();
 
                 Assert.AreEqual(expected, actual, value.ToString("N0", CultureInfo.InvariantCulture));
             }
@@ -90,8 +90,8 @@ namespace X10D.Tests.Core
         {
             for (byte value = 0; value < byte.MaxValue; value++)
             {
-                var expected = _primeNumbers.Contains(value);
-                var actual = value.IsPrime();
+                bool expected = _primeNumbers.Contains(value);
+                bool actual = value.IsPrime();
 
                 Assert.AreEqual(expected, actual, value.ToString("N0", CultureInfo.InvariantCulture));
             }
@@ -107,7 +107,7 @@ namespace X10D.Tests.Core
 
             while (reader.ReadLine() is { } line)
             {
-                if (int.TryParse(line, out var prime))
+                if (int.TryParse(line, out int prime))
                 {
                     primes.Add(prime);
                 }