diff --git a/test/WireMock.Net.Tests/Matchers/JsonPartialWildcardMatcherTests.cs b/test/WireMock.Net.Tests/Matchers/JsonPartialWildcardMatcherTests.cs
index 57a38710..e215d4ad 100644
--- a/test/WireMock.Net.Tests/Matchers/JsonPartialWildcardMatcherTests.cs
+++ b/test/WireMock.Net.Tests/Matchers/JsonPartialWildcardMatcherTests.cs
@@ -338,7 +338,7 @@ public class JsonPartialWildcardMatcherTests
     [InlineData("{ \"test.nested\":\"value\" }", "{\"test\":{\"nested\":\"value1\"}}")]
     [InlineData("{\"test\":{\"test1\":\"value\"}}", "{\"test\":{\"test1\":\"value1\"}}")]
     [InlineData("[{ \"test.nested\":\"value\" }]", "[{\"test\":{\"nested\":\"value1\"}}]")]
-    public void JsonPartialWildcardMatcher_IsMatch_StringInputWithInvalidMatch(string value, string input)
+    public void JsonPartialWildcardMatcher_IsMatch_StringInputWithInvalidMatch(string value, string? input)
     {
         // Assign
         var matcher = new JsonPartialWildcardMatcher(value);
diff --git a/test/WireMock.Net.Tests/Matchers/NotNullOrEmptyMatcherTests.cs b/test/WireMock.Net.Tests/Matchers/NotNullOrEmptyMatcherTests.cs
index 9e8a89a6..8371e1c1 100644
--- a/test/WireMock.Net.Tests/Matchers/NotNullOrEmptyMatcherTests.cs
+++ b/test/WireMock.Net.Tests/Matchers/NotNullOrEmptyMatcherTests.cs
@@ -24,7 +24,7 @@ public class NotNullOrEmptyMatcherTests
     [InlineData(null, 0.0)]
     [InlineData(new byte[0], 0.0)]
     [InlineData(new byte[] { 48 }, 1.0)]
-    public void NotNullOrEmptyMatcher_IsMatch_ByteArray(byte[] data, double expected)
+    public void NotNullOrEmptyMatcher_IsMatch_ByteArray(byte[]? data, double expected)
     {
         // Act
         var matcher = new NotNullOrEmptyMatcher();
@@ -38,7 +38,7 @@ public class NotNullOrEmptyMatcherTests
     [InlineData(null, 0.0)]
     [InlineData("", 0.0)]
     [InlineData("x", 1.0)]
-    public void NotNullOrEmptyMatcher_IsMatch_String(string @string, double expected)
+    public void NotNullOrEmptyMatcher_IsMatch_String(string? @string, double expected)
     {
         // Act
         var matcher = new NotNullOrEmptyMatcher();
@@ -52,11 +52,11 @@ public class NotNullOrEmptyMatcherTests
     [InlineData(null, 0.0)]
     [InlineData("", 0.0)]
     [InlineData("x", 1.0)]
-    public void NotNullOrEmptyMatcher_IsMatch_StringAsObject(string @string, double expected)
+    public void NotNullOrEmptyMatcher_IsMatch_StringAsObject(string? @string, double expected)
     {
         // Act
         var matcher = new NotNullOrEmptyMatcher();
-        var result = matcher.IsMatch((object)@string).Score;
+        var result = matcher.IsMatch((object?)@string).Score;
 
         // Assert
         result.Should().Be(expected);
diff --git a/test/WireMock.Net.Tests/ResponseBuilders/ResponseWithHandlebarsRandomTests.cs b/test/WireMock.Net.Tests/ResponseBuilders/ResponseWithHandlebarsRandomTests.cs
index c4907dca..ad08d598 100644
--- a/test/WireMock.Net.Tests/ResponseBuilders/ResponseWithHandlebarsRandomTests.cs
+++ b/test/WireMock.Net.Tests/ResponseBuilders/ResponseWithHandlebarsRandomTests.cs
@@ -5,7 +5,6 @@ using System.Threading.Tasks;
 using FluentAssertions;
 using Moq;
 using Newtonsoft.Json.Linq;
-using NFluent;
 using WireMock.Handlers;
 using WireMock.Models;
 using WireMock.ResponseBuilders;
@@ -52,10 +51,10 @@ public class ResponseWithHandlebarsRandomTests
         var response = await responseBuilder.ProvideResponseAsync(_mappingMock.Object, request, _settings);
 
         // Assert
-        JObject j = JObject.FromObject(response.Message.BodyData.BodyAsJson);
-        Check.That(j["Text"].Value<string>()).IsNotEmpty();
-        Check.That(j["Integer"].Value<int>()).IsEqualTo(1000);
-        Check.That(j["Long"].Value<long>()).IsStrictlyGreaterThan(77777777).And.IsStrictlyLessThan(99999999);
+        JObject j = JObject.FromObject(response.Message.BodyData!.BodyAsJson!);
+        j["Text"]?.Value<string>().Should().NotBeNullOrEmpty();
+        j["Integer"]?.Value<int>().Should().Be(1000);
+        j["Long"]?.Value<long>().Should().BeInRange(77777777, 99999999);
     }
 
     [Fact]
@@ -75,8 +74,8 @@ public class ResponseWithHandlebarsRandomTests
         var response = await responseBuilder.ProvideResponseAsync(_mappingMock.Object, request, _settings);
 
         // Assert
-        JObject j = JObject.FromObject(response.Message.BodyData.BodyAsJson);
-        Check.That(j["Value"].Type).IsEqualTo(JTokenType.Boolean);
+        JObject j = JObject.FromObject(response.Message.BodyData!.BodyAsJson!);
+        j["Value"]?.Type.Should().Be(JTokenType.Boolean);
     }
 
     [Theory]
@@ -166,9 +165,9 @@ public class ResponseWithHandlebarsRandomTests
         var response = await responseBuilder.ProvideResponseAsync(_mappingMock.Object, request, _settings);
 
         // Assert
-        JObject j = JObject.FromObject(response.Message.BodyData.BodyAsJson);
-        string value = j["StringValue"].Value<string>();
-        Check.That(new[] { "a", "b", "c" }.Contains(value)).IsTrue();
+        JObject j = JObject.FromObject(response.Message.BodyData!.BodyAsJson!);
+        var value = j["StringValue"]?.Value<string>();
+        new[] { "a", "b", "c" }.Should().Contain(value);
     }
 
     [Fact]
@@ -188,8 +187,8 @@ public class ResponseWithHandlebarsRandomTests
         var response = await responseBuilder.ProvideResponseAsync(_mappingMock.Object, request, _settings);
 
         // Assert
-        JObject j = JObject.FromObject(response.Message.BodyData.BodyAsJson);
-        Check.That(j["Integer"].Value<int>()).IsStrictlyGreaterThan(10000000).And.IsStrictlyLessThan(99999999);
+        JObject j = JObject.FromObject(response.Message.BodyData!.BodyAsJson!);
+        j["Integer"]?.Value<int>().Should().BeInRange(10000000, 99999999);
     }
 
     [Fact]
@@ -209,7 +208,7 @@ public class ResponseWithHandlebarsRandomTests
         var response = await responseBuilder.ProvideResponseAsync(_mappingMock.Object, request, _settings);
 
         // Assert
-        var j = JObject.FromObject(response.Message.BodyData.BodyAsJson);
-        j["Long"].Value<long>().Should().BeInRange(1000000000, 9999999999);
+        var j = JObject.FromObject(response.Message.BodyData!.BodyAsJson!);
+        j["Long"]?.Value<long>().Should().BeInRange(1000000000, 9999999999);
     }
 }
\ No newline at end of file
diff --git a/test/WireMock.Net.Tests/Util/FilePathUtilsTests.cs b/test/WireMock.Net.Tests/Util/FilePathUtilsTests.cs
index a53aa5bf..48cea1e4 100644
--- a/test/WireMock.Net.Tests/Util/FilePathUtilsTests.cs
+++ b/test/WireMock.Net.Tests/Util/FilePathUtilsTests.cs
@@ -31,7 +31,7 @@ public class FilePathUtilsTests
     [InlineData(@"\", "")]
     [InlineData(@"\\", "")]
     [InlineData(@"\\a", "a")]
-    public void PathUtils_CleanPath_RemoveLeadingDirectorySeparators(string path, string expected)
+    public void PathUtils_CleanPath_RemoveLeadingDirectorySeparators(string? path, string? expected)
     {
         // Arrange
         var cleanPath = FilePathUtils.CleanPath(path);