diff --git a/src/xunit.analyzers.fixes/X2000/BooleanAssertsShouldNotBeNegatedFixer.cs b/src/xunit.analyzers.fixes/X2000/BooleanAssertsShouldNotBeNegatedFixer.cs
index b8a9b6bb..1be3bed7 100644
--- a/src/xunit.analyzers.fixes/X2000/BooleanAssertsShouldNotBeNegatedFixer.cs
+++ b/src/xunit.analyzers.fixes/X2000/BooleanAssertsShouldNotBeNegatedFixer.cs
@@ -1,3 +1,4 @@
+using System.Collections.Generic;
 using System.Composition;
 using System.Linq;
 using System.Threading;
@@ -57,13 +58,26 @@ static async Task<Document> UseSuggestedAssert(
 		var editor = await DocumentEditor.CreateAsync(document, cancellationToken).ConfigureAwait(false);
 
 		if (invocation.Expression is MemberAccessExpressionSyntax memberAccess)
+		{
 			if (invocation.ArgumentList.Arguments[0].Expression is PrefixUnaryExpressionSyntax prefixUnaryExpression)
+			{
+				var originalArguments = invocation.ArgumentList.Arguments;
+				var newFirstArgument = Argument(prefixUnaryExpression.Operand);
+
+				var newArguments = new List<ArgumentSyntax> { newFirstArgument };
+				if (originalArguments.Count > 1)
+				{
+					newArguments.AddRange(originalArguments.Skip(1));
+				}
+
 				editor.ReplaceNode(
 					invocation,
 					invocation
-						.WithArgumentList(ArgumentList(SeparatedList([Argument(prefixUnaryExpression.Operand)])))
+						.WithArgumentList(ArgumentList(SeparatedList(newArguments)))
 						.WithExpression(memberAccess.WithName(IdentifierName(replacement)))
 				);
+			}
+		}
 
 		return editor.GetChangedDocument();
 	}
diff --git a/src/xunit.analyzers.tests/Fixes/X2000/BooleanAssertsShouldNotBeNegatedFixerTests.cs b/src/xunit.analyzers.tests/Fixes/X2000/BooleanAssertsShouldNotBeNegatedFixerTests.cs
index cdc8c9db..e950b9a9 100644
--- a/src/xunit.analyzers.tests/Fixes/X2000/BooleanAssertsShouldNotBeNegatedFixerTests.cs
+++ b/src/xunit.analyzers.tests/Fixes/X2000/BooleanAssertsShouldNotBeNegatedFixerTests.cs
@@ -6,17 +6,17 @@
 public class BooleanAssertsShouldNotBeNegatedFixerTests
 {
 	const string template = /* lang=c#-test */ """
-		using Xunit;
+	using Xunit;
 
-		public class TestClass {{
-			[Fact]
-			public void TestMethod() {{
-				bool condition = true;
+	public class TestClass {{
+		[Fact]
+		public void TestMethod() {{
+			bool condition = true;
 
-				{0};
-			}}
+			{0};
 		}}
-		""";
+	}}
+	""";
 
 	[Theory]
 	[InlineData("False", "True")]
@@ -30,4 +30,66 @@ public async Task ReplacesBooleanAssert(
 
 		await Verify.VerifyCodeFix(before, after, BooleanAssertsShouldNotBeNegatedFixer.Key_UseSuggestedAssert);
 	}
+
+	[Theory]
+	[InlineData("False", "True")]
+	[InlineData("True", "False")]
+	public async Task PreservesUserMessageNamedParameter(
+		string assertion,
+		string replacement)
+	{
+		var before = string.Format(template, $"[|Assert.{assertion}(!condition, userMessage: \"test message\")|]");
+		var after = string.Format(template, $"Assert.{replacement}(condition, userMessage: \"test message\")");
+
+		await Verify.VerifyCodeFix(before, after, BooleanAssertsShouldNotBeNegatedFixer.Key_UseSuggestedAssert);
+	}
+
+	[Theory]
+	[InlineData("False", "True")]
+	[InlineData("True", "False")]
+	public async Task PreservesUserMessagePositionalParameter(
+		string assertion,
+		string replacement)
+	{
+		var before = string.Format(template, $"[|Assert.{assertion}(!condition, \"test message\")|]");
+		var after = string.Format(template, $"Assert.{replacement}(condition, \"test message\")");
+
+		await Verify.VerifyCodeFix(before, after, BooleanAssertsShouldNotBeNegatedFixer.Key_UseSuggestedAssert);
+	}
+
+	[Fact]
+	public async Task PreservesWhitespace()
+	{
+		var before = string.Format(template, "[|Assert.True(   !condition   )|]");
+		var after = string.Format(template, "Assert.False(condition)");
+
+		await Verify.VerifyCodeFix(before, after, BooleanAssertsShouldNotBeNegatedFixer.Key_UseSuggestedAssert);
+	}
+
+	[Fact]
+	public async Task NegatedLiteral()
+	{
+		var before = string.Format(template, "[|Assert.True(!false)|]");
+		var after = string.Format(template, "Assert.False(false)");
+
+		await Verify.VerifyCodeFix(before, after, BooleanAssertsShouldNotBeNegatedFixer.Key_UseSuggestedAssert);
+	}
+
+	[Fact]
+	public async Task NegatedPropertyAccess()
+	{
+		var before = string.Format(template, "[|Assert.True(!condition)|]");
+		var after = string.Format(template, "Assert.False(condition)");
+
+		await Verify.VerifyCodeFix(before, after, BooleanAssertsShouldNotBeNegatedFixer.Key_UseSuggestedAssert);
+	}
+
+	[Fact]
+	public async Task PreservesUserMessageWithComplexExpression()
+	{
+		var before = string.Format(template, "[|Assert.True(!false, userMessage: \"test\")|]");
+		var after = string.Format(template, "Assert.False(false, userMessage: \"test\")");
+
+		await Verify.VerifyCodeFix(before, after, BooleanAssertsShouldNotBeNegatedFixer.Key_UseSuggestedAssert);
+	}
 }