diff --git a/templates/repo/diff/section_split.tmpl b/templates/repo/diff/section_split.tmpl
index 182fa737e..7b1f72939 100644
--- a/templates/repo/diff/section_split.tmpl
+++ b/templates/repo/diff/section_split.tmpl
@@ -18,17 +18,17 @@
 					<td class="lines-num lines-num-old">
 						<div class="tw-flex">
 						{{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 5)}}
-							<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.RepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=split&direction=down&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
+							<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.CommitRepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=split&direction=down&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
 								{{svg "octicon-fold-down"}}
 							</button>
 						{{end}}
 						{{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 4)}}
-							<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.RepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=split&direction=up&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
+							<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.CommitRepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=split&direction=up&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
 								{{svg "octicon-fold-up"}}
 							</button>
 						{{end}}
 						{{if eq $line.GetExpandDirection 2}}
-							<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.RepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=split&direction=&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
+							<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.CommitRepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=split&direction=&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
 								{{svg "octicon-fold"}}
 							</button>
 						{{end}}
diff --git a/templates/repo/diff/section_unified.tmpl b/templates/repo/diff/section_unified.tmpl
index 018c169dc..d7fe75895 100644
--- a/templates/repo/diff/section_unified.tmpl
+++ b/templates/repo/diff/section_unified.tmpl
@@ -14,17 +14,17 @@
 					<td colspan="2" class="lines-num">
 						<div class="tw-flex">
 							{{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 5)}}
-								<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.RepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=unified&direction=down&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
+								<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.CommitRepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=unified&direction=down&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
 									{{svg "octicon-fold-down"}}
 								</button>
 							{{end}}
 							{{if or (eq $line.GetExpandDirection 3) (eq $line.GetExpandDirection 4)}}
-								<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.RepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=unified&direction=up&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
+								<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.CommitRepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=unified&direction=up&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
 									{{svg "octicon-fold-up"}}
 								</button>
 							{{end}}
 							{{if eq $line.GetExpandDirection 2}}
-								<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.RepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=unified&direction=&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
+								<button class="code-expander-button" hx-target="closest tr" hx-get="{{$.root.CommitRepoLink}}/blob_excerpt/{{PathEscape $.root.AfterCommitID}}?{{$line.GetBlobExcerptQuery}}&style=unified&direction=&wiki={{$.root.PageIsWiki}}&anchor=diff-{{$file.NameHash}}K{{$line.SectionInfo.RightIdx}}">
 									{{svg "octicon-fold"}}
 								</button>
 							{{end}}
diff --git a/tests/integration/compare_test.go b/tests/integration/compare_test.go
index 88a7c761d..ffcdd2f23 100644
--- a/tests/integration/compare_test.go
+++ b/tests/integration/compare_test.go
@@ -15,8 +15,11 @@ import (
 	repo_model "code.gitea.io/gitea/models/repo"
 	unit_model "code.gitea.io/gitea/models/unit"
 	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/gitrepo"
+	"code.gitea.io/gitea/modules/optional"
 	repo_service "code.gitea.io/gitea/services/repository"
+	files_service "code.gitea.io/gitea/services/repository/files"
 	"code.gitea.io/gitea/tests"
 
 	"github.com/stretchr/testify/assert"
@@ -213,3 +216,43 @@ func TestCompareCrossRepo(t *testing.T) {
 		})
 	})
 }
+
+func TestCompareCodeExpand(t *testing.T) {
+	onGiteaRun(t, func(t *testing.T, u *url.URL) {
+		owner := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+
+		// Create a new repository, with a file that has many lines
+		repo, _, f := CreateDeclarativeRepoWithOptions(t, owner, DeclarativeRepoOptions{
+			Files: optional.Some([]*files_service.ChangeRepoFile{
+				{
+					Operation:     "create",
+					TreePath:      "docs.md",
+					ContentReader: strings.NewReader("01\n02\n03\n04\n05\n06\n07\n08\n09\n0a\n0b\n0c\n0d\n0e\n0f\n10\n11\n12\n12\n13\n14\n15\n16\n17\n18\n19\n1a\n1b\n1c\n1d\n1e\n1f\n20\n"),
+				},
+			}),
+		})
+		defer f()
+
+		// Fork the repository
+		forker := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
+		session := loginUser(t, forker.Name)
+		testRepoFork(t, session, owner.Name, repo.Name, forker.Name, repo.Name+"-copy")
+		testCreateBranch(t, session, forker.Name, repo.Name+"-copy", "branch/main", "code-expand", http.StatusSeeOther)
+
+		// Edit the file, insert a line somewhere in the middle
+		testEditFile(t, session, forker.Name, repo.Name+"-copy", "code-expand", "docs.md",
+			"01\n02\n03\n04\n05\n06\n07\n08\n09\n0a\n0b\n0c\n0d\n0e\n0f\n10\n11\nHELLO WORLD!\n12\n12\n13\n14\n15\n16\n17\n18\n19\n1a\n1b\n1c\n1d\n1e\n1f\n20\n",
+		)
+
+		t.Run("code expander targets the fork", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			req := NewRequestf(t, "GET", "%s/%s/compare/main...%s/%s:code-expand",
+				owner.Name, repo.Name, forker.Name, repo.Name+"-copy")
+			resp := session.MakeRequest(t, req, http.StatusOK)
+			htmlDoc := NewHTMLParser(t, resp.Body)
+			htmlDoc.AssertElement(t, fmt.Sprintf("button.code-expander-button[hx-get^='/%s/%s/blob_excerpt/'] svg.octicon-fold-up", forker.Name, repo.Name+"-copy"), true)
+			htmlDoc.AssertElement(t, fmt.Sprintf("button.code-expander-button[hx-get^='/%s/%s/blob_excerpt/'] svg.octicon-fold-down", forker.Name, repo.Name+"-copy"), true)
+		})
+	})
+}