diff --git a/src/SixLabors.Core/Helpers/Guard.cs b/src/SixLabors.Core/Helpers/Guard.cs
index e433de44e..4a738d8b3 100644
--- a/src/SixLabors.Core/Helpers/Guard.cs
+++ b/src/SixLabors.Core/Helpers/Guard.cs
@@ -56,7 +56,7 @@ namespace SixLabors
                     throw new ArgumentException(message, parameterName);
                 }
 
-                throw new ArgumentException("Value cannot be null or empty and cannot contain only blanks.", parameterName);
+                throw new ArgumentException("Value cannot be null, empty, or cannot contain only whitespace.", parameterName);
             }
         }
 
@@ -92,7 +92,7 @@ namespace SixLabors
         /// <param name="max">The maximum value.</param>
         /// <param name="parameterName">The name of the parameter that is to be checked.</param>
         /// <typeparam name="TValue">The type of the value.</typeparam>
-        /// <exception cref="ArgumentException">
+        /// <exception cref="ArgumentOutOfRangeException">
         /// <paramref name="value"/> is greater than the maximum value.
         /// </exception>
         public static void MustBeLessThan<TValue>(TValue value, TValue max, string parameterName)
@@ -112,7 +112,7 @@ namespace SixLabors
         /// <param name="max">The maximum value.</param>
         /// <param name="parameterName">The name of the parameter that is to be checked.</param>
         /// <typeparam name="TValue">The type of the value.</typeparam>
-        /// <exception cref="ArgumentException">
+        /// <exception cref="ArgumentOutOfRangeException">
         /// <paramref name="value"/> is greater than the maximum value.
         /// </exception>
         public static void MustBeLessThanOrEqualTo<TValue>(TValue value, TValue max, string parameterName)
@@ -132,7 +132,7 @@ namespace SixLabors
         /// <param name="min">The minimum value.</param>
         /// <param name="parameterName">The name of the parameter that is to be checked.</param>
         /// <typeparam name="TValue">The type of the value.</typeparam>
-        /// <exception cref="ArgumentException">
+        /// <exception cref="ArgumentOutOfRangeException">
         /// <paramref name="value"/> is less than the minimum value.
         /// </exception>
         public static void MustBeGreaterThan<TValue>(TValue value, TValue min, string parameterName)
@@ -140,9 +140,7 @@ namespace SixLabors
         {
             if (value.CompareTo(min) <= 0)
             {
-                throw new ArgumentOutOfRangeException(
-                    parameterName,
-                    $"Value must be greater than {min}.");
+                throw new ArgumentOutOfRangeException(parameterName, $"Value must be greater than {min}.");
             }
         }
 
@@ -154,7 +152,7 @@ namespace SixLabors
         /// <param name="min">The minimum value.</param>
         /// <param name="parameterName">The name of the parameter that is to be checked.</param>
         /// <typeparam name="TValue">The type of the value.</typeparam>
-        /// <exception cref="ArgumentException">
+        /// <exception cref="ArgumentOutOfRangeException">
         /// <paramref name="value"/> is less than the minimum value.
         /// </exception>
         public static void MustBeGreaterThanOrEqualTo<TValue>(TValue value, TValue min, string parameterName)
@@ -175,7 +173,7 @@ namespace SixLabors
         /// <param name="max">The maximum value.</param>
         /// <param name="parameterName">The name of the parameter that is to be checked.</param>
         /// <typeparam name="TValue">The type of the value.</typeparam>
-        /// <exception cref="ArgumentException">
+        /// <exception cref="ArgumentOutOfRangeException">
         /// <paramref name="value"/> is less than the minimum value of greater than the maximum value.
         /// </exception>
         public static void MustBeBetweenOrEqualTo<TValue>(TValue value, TValue min, TValue max, string parameterName)
@@ -191,7 +189,7 @@ namespace SixLabors
         /// Verifies, that the method parameter with specified target value is true
         /// and throws an exception if it is found to be so.
         /// </summary>
-        /// <param name="target">
+        /// <param name="value">
         /// The target value, which cannot be false.
         /// </param>
         /// <param name="parameterName">
@@ -201,11 +199,11 @@ namespace SixLabors
         /// The error message, if any to add to the exception.
         /// </param>
         /// <exception cref="ArgumentException">
-        /// <paramref name="target"/> is false
+        /// <paramref name="value"/> is false
         /// </exception>
-        public static void IsTrue(bool target, string parameterName, string message)
+        public static void IsTrue(bool value, string parameterName, string message)
         {
-            if (!target)
+            if (!value)
             {
                 throw new ArgumentException(message, parameterName);
             }
@@ -215,35 +213,35 @@ namespace SixLabors
         /// Verifies, that the method parameter with specified target value is false
         /// and throws an exception if it is found to be so.
         /// </summary>
-        /// <param name="target">The target value, which cannot be true.</param>
+        /// <param name="value">The target value, which cannot be true.</param>
         /// <param name="parameterName">The name of the parameter that is to be checked.</param>
         /// <param name="message">The error message, if any to add to the exception.</param>
         /// <exception cref="ArgumentException">
-        /// <paramref name="target"/> is true
+        /// <paramref name="value"/> is true
         /// </exception>
-        public static void IsFalse(bool target, string parameterName, string message)
+        public static void IsFalse(bool value, string parameterName, string message)
         {
-            if (target)
+            if (value)
             {
                 throw new ArgumentException(message, parameterName);
             }
         }
 
         /// <summary>
-        /// Verifies, that the `target` span has the length of 'minSpan', or longer.
+        /// Verifies, that the `target` span has the length of 'minLength', or longer.
         /// </summary>
         /// <typeparam name="T">The element type of the spans</typeparam>
-        /// <param name="target">The target span.</param>
+        /// <param name="value">The target span.</param>
         /// <param name="minLength">The minimum length.</param>
         /// <param name="parameterName">The name of the parameter that is to be checked.</param>
         /// <exception cref="ArgumentException">
-        /// <paramref name="target"/> is true
+        /// The length of <paramref name="value"/> is less than <paramref name="minLength"/>.
         /// </exception>
-        public static void MustBeSizedAtLeast<T>(ReadOnlySpan<T> target, int minLength, string parameterName)
+        public static void MustBeSizedAtLeast<T>(ReadOnlySpan<T> value, int minLength, string parameterName)
         {
-            if (target.Length < minLength)
+            if (value.Length < minLength)
             {
-                throw new ArgumentException($"Span-s must be at least of length {minLength}!", parameterName);
+                throw new ArgumentException($"The size must be at least {minLength}.", parameterName);
             }
         }
     }
diff --git a/tests/SixLabors.Core.Tests/Helpers/GuardTests.cs b/tests/SixLabors.Core.Tests/Helpers/GuardTests.cs
new file mode 100644
index 000000000..c91ebbcd6
--- /dev/null
+++ b/tests/SixLabors.Core.Tests/Helpers/GuardTests.cs
@@ -0,0 +1,286 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Xunit;
+
+namespace SixLabors.Helpers.Tests
+{
+    public class GuardTests
+    {
+        [Fact]
+        public void NotNull_TargetNotNull_ThrowsNoException()
+        {
+            Guard.NotNull("test", "myParamName");
+        }
+
+        [Fact]
+        public void NotNull_TargetNull_ThrowsException()
+        {
+            Assert.Throws<ArgumentNullException>(() =>
+            {
+                Guard.NotNull(null, "myParamName");
+            });
+        }
+
+        [Fact]
+        public void NotNull_TargetNullWithMessage_ThrowsException()
+        {
+            var exception = Assert.Throws<ArgumentNullException>(() =>
+            {
+                Guard.NotNull(null, "myParamName", "myTestMessage");
+            });
+
+            Assert.Equal("myParamName", exception.ParamName);
+            Assert.True(exception.Message.Contains("myTestMessage"));
+        }
+
+        [Fact]
+        public void NotNullOrEmpty_TargetNotNullOrEmpty_ThrowsNoException()
+        {
+            Guard.NotNullOrEmpty("test", "myParamName");
+        }
+
+        [Fact]
+        public void NotNullOrEmpty_TargetNull_ThrowsException()
+        {
+            Assert.Throws<ArgumentNullException>(() =>
+            {
+                Guard.NotNullOrEmpty(null, "myParamName");
+            });
+        }
+
+        [Fact]
+        public void NotNullOrEmpty_TargetWhitespace_ThrowsException()
+        {
+            Assert.Throws<ArgumentException>(() =>
+            {
+                Guard.NotNullOrEmpty("\n\n", "myParamName");
+            });
+        }
+
+        [Fact]
+        public void NotNullOrEmpty_TargetEmpty_ThrowsException()
+        {
+            var exception = Assert.Throws<ArgumentException>(() =>
+            {
+                Guard.NotNullOrEmpty(string.Empty, "myParamName");
+            });
+
+            Assert.Equal("myParamName", exception.ParamName);
+            Assert.True(exception.Message.Contains("Value cannot be null, empty, or cannot contain only whitespace."));
+        }
+
+        [Fact]
+        public void NotNullOrEmpty_TargetEmptyWithMessage_ThrowsException()
+        {
+            var exception = Assert.Throws<ArgumentException>(() =>
+            {
+                Guard.NotNullOrEmpty(string.Empty, "myParamName", "myTestMessage");
+            });
+
+            Assert.Equal("myParamName", exception.ParamName);
+            Assert.True(exception.Message.Contains("myTestMessage"));
+        }
+
+        [Fact]
+        public void NotNullOrEmptyIEnumerable_TargetNotNullOrEmpty_ThrowsNoException()
+        {
+            Guard.NotNullOrEmpty(new string[] { "test" }, "myParamName");
+        }
+
+        [Fact]
+        public void NotNullOrEmptyIEnumerable_TargetNull_ThrowsException()
+        {
+            Assert.Throws<ArgumentNullException>(() =>
+            {
+                Guard.NotNullOrEmpty((IEnumerable<string>)null, "myParamName");
+            });
+        }
+
+        [Fact]
+        public void NotNullOrEmptyIEnumerable_TargetEmpty_ThrowsException()
+        {
+            var exception = Assert.Throws<ArgumentException>(() =>
+            {
+                Guard.NotNullOrEmpty(new string[] { }, "myParamName");
+            });
+
+            Assert.Equal("myParamName", exception.ParamName);
+            Assert.True(exception.Message.Contains("Value cannot be empty."));
+        }
+
+        [Fact]
+        public void NotNullOrEmptyIEnumerable_TargetEmptyWithMessage_ThrowsException()
+        {
+            var exception = Assert.Throws<ArgumentException>(() =>
+            {
+                Guard.NotNullOrEmpty(new string[] { }, "myParamName", "myTestMessage");
+            });
+
+            Assert.Equal("myParamName", exception.ParamName);
+            Assert.True(exception.Message.Contains("myTestMessage"));
+        }
+
+        [Fact]
+        public void MustBeLessThan_IsLess_ThrowsNoException()
+        {
+            Guard.MustBeLessThan(0, 1, "myParamName");
+        }
+
+        [Theory]
+        [InlineData(2, 1)]
+        [InlineData(1, 1)]
+        public void MustBeLessThan_IsGreaterOrEqual_ThrowsNoException(int value, int max)
+        {
+            var exception = Assert.Throws<ArgumentOutOfRangeException>(() =>
+            {
+                Guard.MustBeLessThan(value, max, "myParamName");
+            });
+
+            Assert.Equal("myParamName", exception.ParamName);
+            Assert.True(exception.Message.Contains($"Value must be less than {max}."));
+        }
+
+        [Theory]
+        [InlineData(0, 1)]
+        [InlineData(1, 1)]
+        public void MustBeLessThanOrEqualTo_IsLessOrEqual_ThrowsNoException(int value, int max)
+        {
+            Guard.MustBeLessThanOrEqualTo(value, max, "myParamName");
+        }
+
+        [Fact]
+        public void MustBeLessThanOrEqualTo_IsGreater_ThrowsNoException()
+        {
+            var exception = Assert.Throws<ArgumentOutOfRangeException>(() =>
+            {
+                Guard.MustBeLessThanOrEqualTo(2, 1, "myParamName");
+            });
+
+            Assert.Equal("myParamName", exception.ParamName);
+            Assert.True(exception.Message.Contains($"Value must be less than or equal to 1."));
+        }
+
+        [Fact]
+        public void MustBeGreaterThan_IsGreater_ThrowsNoException()
+        {
+            Guard.MustBeGreaterThan(2, 1, "myParamName");
+        }
+
+        [Theory]
+        [InlineData(1, 2)]
+        [InlineData(1, 1)]
+        public void MustBeGreaterThan_IsLessOrEqual_ThrowsNoException(int value, int min)
+        {
+            var exception = Assert.Throws<ArgumentOutOfRangeException>(() =>
+            {
+                Guard.MustBeGreaterThan(value, min, "myParamName");
+            });
+
+            Assert.Equal("myParamName", exception.ParamName);
+            Assert.True(exception.Message.Contains($"Value must be greater than {min}."));
+        }
+
+        [Theory]
+        [InlineData(2, 1)]
+        [InlineData(1, 1)]
+        public void MustBeGreaterThanOrEqualTo_IsGreaterOrEqual_ThrowsNoException(int value, int min)
+        {
+            Guard.MustBeGreaterThanOrEqualTo(value, min, "myParamName");
+        }
+
+        [Fact]
+        public void MustBeGreaterThanOrEqualTo_IsLess_ThrowsNoException()
+        {
+            var exception = Assert.Throws<ArgumentOutOfRangeException>(() =>
+            {
+                Guard.MustBeGreaterThanOrEqualTo(1, 2, "myParamName");
+            });
+
+            Assert.Equal("myParamName", exception.ParamName);
+            Assert.True(exception.Message.Contains($"Value must be greater than or equal to 2."));
+        }
+
+        [Theory]
+        [InlineData(1, 1, 3)]
+        [InlineData(2, 1, 3)]
+        [InlineData(3, 1, 3)]
+        public void MustBeBetweenOrEqualTo_IsBetweenOrEqual_ThrowsNoException(int value, int min, int max)
+        {
+            Guard.MustBeBetweenOrEqualTo(value, min, max, "myParamName");
+        }
+
+        [Theory]
+        [InlineData(0, 1, 3)]
+        [InlineData(4, 1, 3)]
+        public void MustBeBetweenOrEqualTo_IsLessOrGreater_ThrowsNoException(int value, int min, int max)
+        {
+            var exception = Assert.Throws<ArgumentOutOfRangeException>(() =>
+            {
+                Guard.MustBeBetweenOrEqualTo(value, min, max, "myParamName");
+            });
+
+            Assert.Equal("myParamName", exception.ParamName);
+            Assert.True(exception.Message.Contains($"Value must be greater than or equal to {min} and less than or equal to {max}."));
+        }
+
+        [Fact]
+        public void IsTrue_IsTrue_ThrowsNoException()
+        {
+            Guard.IsTrue(true, "myParamName", "myTestMessage");
+        }
+
+        [Fact]
+        public void IsTrue_IsFalse_ThrowsException()
+        {
+            var exception = Assert.Throws<ArgumentException>(() =>
+            {
+                Guard.IsTrue(false, "myParamName", "myTestMessage");
+            });
+
+            Assert.Equal("myParamName", exception.ParamName);
+            Assert.True(exception.Message.Contains("myTestMessage"));
+        }
+
+        [Fact]
+        public void IsFalse_IsFalse_ThrowsNoException()
+        {
+            Guard.IsFalse(false, "myParamName", "myTestMessage");
+        }
+
+        [Fact]
+        public void IsFalse_IsTrue_ThrowsException()
+        {
+            var exception = Assert.Throws<ArgumentException>(() =>
+            {
+                Guard.IsFalse(true, "myParamName", "myTestMessage");
+            });
+
+            Assert.Equal("myParamName", exception.ParamName);
+            Assert.True(exception.Message.Contains("myTestMessage"));
+        }
+
+        [Theory]
+        [InlineData(new int[] { 1, 2 }, 1)]
+        [InlineData(new int[] { 1, 2 }, 2)]
+        public void MustBeSizedAtLeast_LengthIsGreaterOrEqual_ThrowsNoException(int[] value, int minLength)
+        {
+            Guard.MustBeSizedAtLeast<int>(value, minLength, "myParamName");
+        }
+
+        [Fact]
+        public void MustBeSizedAtLeast_LengthIsLess_ThrowsException()
+        {
+            var exception = Assert.Throws<ArgumentException>(() =>
+            {
+                Guard.MustBeSizedAtLeast<int>(new int[] { 1, 2 }, 3, "myParamName");
+            });
+
+            Assert.Equal("myParamName", exception.ParamName);
+            Assert.True(exception.Message.Contains($"The size must be at least 3."));
+        }
+    }
+}