diff --git a/src/IDisposableGenerator/DisposableCodeWriter.cs b/src/IDisposableGenerator/DisposableCodeWriter.cs
index b16ede9..342c976 100644
--- a/src/IDisposableGenerator/DisposableCodeWriter.cs
+++ b/src/IDisposableGenerator/DisposableCodeWriter.cs
@@ -227,7 +227,7 @@ namespace {workItem.Namespace};
             // inject the created sources into the users compilation.
             sourceBuilder.ToString().ToSourceFile($@"Disposables{(
                 workItemCollection.GetWorkItems().Count > 1
-                    ? $"{workItemCollection.GetWorkItems().IndexOf(workItem)}" :
+                    ? $".{workItemCollection.GetWorkItems().IndexOf(workItem)}" :
                     string.Empty)}.g.cs", ref context);
         }
     }
diff --git a/tests/IDisposableGeneratorTests.CSharp10.cs b/tests/IDisposableGeneratorTests.CSharp10.cs
index 7a29a1e..9862862 100644
--- a/tests/IDisposableGeneratorTests.CSharp10.cs
+++ b/tests/IDisposableGeneratorTests.CSharp10.cs
@@ -325,4 +325,99 @@ internal partial class TestDisposable
     public string? test { get; set; } = ""stuff here."";
 }
 ", LanguageVersion.CSharp10).ConfigureAwait(false);
+
+    [Fact]
+    public async Task TestGeneratingDisposableWithMultipleNamespacesCSharp10()
+    {
+        var testSources = new List<string>
+        {
+            @"namespace MyApp.AnotherNamespace;
+
+[GenerateDispose(false)]
+internal partial class AnotherDisposable
+{
+}
+",
+        };
+        var generatedSources = new Dictionary<string, string>
+        {
+            {"Disposables.0.g.cs", @"// <autogenerated/>
+namespace MyApp;
+
+internal partial class TestDisposable : IDisposable
+{
+    private bool isDisposed;
+
+    /// <summary>
+    /// Cleans up the resources used by <see cref=""TestDisposable""/>.
+    /// </summary>
+    public void Dispose() => this.Dispose(true);
+
+    private void Dispose(bool disposing)
+    {
+        if (!this.isDisposed && disposing)
+        {
+            this.test = null;
+            this.isDisposed = true;
+        }
+    }
+}
+"},
+            {"Disposables.1.g.cs", @"// <autogenerated/>
+namespace MyApp.AnotherNamespace;
+
+internal partial class AnotherDisposable : IDisposable
+{
+    private bool isDisposed;
+
+    /// <summary>
+    /// Cleans up the resources used by <see cref=""AnotherDisposable""/>.
+    /// </summary>
+    public void Dispose() => this.Dispose(true);
+
+    private void Dispose(bool disposing)
+    {
+        if (!this.isDisposed && disposing)
+        {
+            this.isDisposed = true;
+        }
+    }
+}
+"}
+        };
+        await RunTest<CSGeneratorTest>(@"// <autogenerated/>
+namespace MyApp;
+
+internal partial class TestDisposable : IDisposable
+{
+    private bool isDisposed;
+
+    /// <summary>
+    /// Cleans up the resources used by <see cref=""TestDisposable""/>.
+    /// </summary>
+    public void Dispose() => this.Dispose(true);
+
+    private void Dispose(bool disposing)
+    {
+        if (!this.isDisposed && disposing)
+        {
+            this.test = null;
+            this.isDisposed = true;
+        }
+    }
+}
+", @"global using System;
+global using System.ComponentModel.DataAnnotations;
+global using IDisposableGenerator;
+
+namespace MyApp;
+
+[GenerateDispose(false)]
+internal partial class TestDisposable
+{
+    [NullOnDispose]
+    public string? test { get; set; } = ""stuff here."";
+}
+", LanguageVersion.CSharp10, testSources, generatedSources).ConfigureAwait(false);
+    }
 }
diff --git a/tests/IDisposableGeneratorTests.cs b/tests/IDisposableGeneratorTests.cs
index 200fe39..b7f7f25 100644
--- a/tests/IDisposableGeneratorTests.cs
+++ b/tests/IDisposableGeneratorTests.cs
@@ -12,7 +12,9 @@ public async Task TestGeneratingNoInput()
     private static async Task RunTest<TestType>(
         string generatedSource,
         string testSource,
-        LanguageVersion? languageVersion = LanguageVersion.CSharp9)
+        LanguageVersion? languageVersion = LanguageVersion.CSharp9,
+        List<string>? testSources = null,
+        Dictionary<string, string>? generatedSources = null)
         where TestType : SourceGeneratorTest<XUnitVerifier>, IGeneratorTestBase, new()
     {
         var test = new TestType
@@ -35,8 +37,26 @@ private static async Task RunTest<TestType>(
                 var generatedAttributeSource = Properties.Resources.AttributeCodeCSharp!;
                 test.TestState.GeneratedSources.Add(
                     (typeof(IDisposableGenerator), "GeneratedAttributes.g.cs", generatedAttributeSource));
-                test.TestState.GeneratedSources.Add(
-                    (typeof(IDisposableGenerator), "Disposables.g.cs", generatedSource));
+                if (generatedSources is not null
+                    && languageVersion == LanguageVersion.CSharp10)
+                {
+                    foreach (var source in testSources!)
+                    {
+                        test.TestState.Sources.Add(source);
+                    }
+
+                    foreach (var (key, value) in generatedSources)
+                    {
+                        test.TestState.GeneratedSources.Add(
+                            (typeof(IDisposableGenerator), key, value));
+                    }
+                }
+                else
+                {
+                    test.TestState.GeneratedSources.Add(
+                        (typeof(IDisposableGenerator), "Disposables.g.cs", generatedSource));
+                }
+
                 break;
             }
             case false when test is VBGeneratorTest: