diff --git a/KoeBook.Test/Epub/EpubDocumentTest.cs b/KoeBook.Test/Epub/EpubDocumentTest.cs
index c36a83b..e5868a8 100644
--- a/KoeBook.Test/Epub/EpubDocumentTest.cs
+++ b/KoeBook.Test/Epub/EpubDocumentTest.cs
@@ -8,7 +8,7 @@ public class EpubDocumentTest
     [Fact]
     public void EnsureChapter()
     {
-        var document = new EpubDocument("title", "author", "cover", default);
+        var document = new EpubDocument("title", "author", default);
 
         Assert.Empty(document.Chapters);
 
@@ -29,7 +29,7 @@ public void EnsureChapter()
     [Fact]
     public void EnsureSection()
     {
-        var document = new EpubDocument("title", "author", "cover", default);
+        var document = new EpubDocument("title", "author", default);
 
         Assert.Empty(document.Chapters);
 
@@ -77,7 +77,7 @@ public void EnsureSection()
     [Fact]
     public void EnsureParagraph()
     {
-        var document = new EpubDocument("title", "author", "cover", default);
+        var document = new EpubDocument("title", "author", default);
 
         Assert.Empty(document.Chapters);
 
diff --git a/KoeBook.Test/Epub/ScrapingAozoraServiceTest.cs b/KoeBook.Test/Epub/ScrapingAozoraServiceTest.cs
index 7a46dc5..6a1e7df 100644
--- a/KoeBook.Test/Epub/ScrapingAozoraServiceTest.cs
+++ b/KoeBook.Test/Epub/ScrapingAozoraServiceTest.cs
@@ -28,7 +28,7 @@ public async Task AddParagraphs1(string input, string[] expected)
         using var context = BrowsingContext.New(Configuration.Default);
         using var doc = await context.OpenAsync(req => req.Content(input));
         Assert.NotNull(doc.ParentElement);
-        var epubDocument = new EpubDocument("title", "author", "", default)
+        var epubDocument = new EpubDocument("title", "author", default)
         {
             Chapters = [new() { Sections = [new("section title") { Elements = [new Paragraph() { Text = "test" }] }] }]
         };