diff --git a/.golangci.yml b/.golangci.yml
index 80bd856ccfb..12d08ec69f1 100644
--- a/.golangci.yml
+++ b/.golangci.yml
@@ -92,9 +92,6 @@ linters:
       ignore-rules:
         - analyses # returned by the GitHub API
         - cancelled # returned by the GitHub API
-    modernize:
-      disable:
-        - omitzero # TODO: fix
     nolintlint:
       allow-unused: true
       require-specific: true
diff --git a/github/activity_notifications.go b/github/activity_notifications.go
index e712323ed43..feb38ea3391 100644
--- a/github/activity_notifications.go
+++ b/github/activity_notifications.go
@@ -101,10 +101,11 @@ func (s *ActivityService) ListRepositoryNotifications(ctx context.Context, owner
 }
 
 type markReadOptions struct {
-	LastReadAt Timestamp `json:"last_read_at,omitempty"`
+	LastReadAt Timestamp `json:"last_read_at,omitzero"`
 }
 
 // MarkNotificationsRead marks all notifications up to lastRead as read.
+// If lastRead is the zero value, all notifications in the repository are marked as read.
 //
 // GitHub API docs: https://docs.github.com/rest/activity/notifications#mark-notifications-as-read
 //
@@ -123,6 +124,7 @@ func (s *ActivityService) MarkNotificationsRead(ctx context.Context, lastRead Ti
 
 // MarkRepositoryNotificationsRead marks all notifications up to lastRead in
 // the specified repository as read.
+// If lastRead is the zero value, all notifications in the repository are marked as read.
 //
 // GitHub API docs: https://docs.github.com/rest/activity/notifications#mark-repository-notifications-as-read
 //
diff --git a/github/activity_notifications_test.go b/github/activity_notifications_test.go
index 7744f1e6a3d..b0d25645ab2 100644
--- a/github/activity_notifications_test.go
+++ b/github/activity_notifications_test.go
@@ -117,6 +117,25 @@ func TestActivityService_MarkNotificationsRead(t *testing.T) {
 	})
 }
 
+func TestActivityService_MarkNotificationsRead_EmptyLastReadAt(t *testing.T) {
+	t.Parallel()
+	client, mux, _ := setup(t)
+
+	mux.HandleFunc("/notifications", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "PUT")
+		testHeader(t, r, "Content-Type", "application/json")
+		testBody(t, r, `{}`+"\n")
+
+		w.WriteHeader(http.StatusResetContent)
+	})
+
+	ctx := t.Context()
+	_, err := client.Activity.MarkNotificationsRead(ctx, Timestamp{})
+	if err != nil {
+		t.Errorf("Activity.MarkNotificationsRead returned error: %v", err)
+	}
+}
+
 func TestActivityService_MarkRepositoryNotificationsRead(t *testing.T) {
 	t.Parallel()
 	client, mux, _ := setup(t)
@@ -146,6 +165,25 @@ func TestActivityService_MarkRepositoryNotificationsRead(t *testing.T) {
 	})
 }
 
+func TestActivityService_MarkRepositoryNotificationsRead_EmptyLastReadAt(t *testing.T) {
+	t.Parallel()
+	client, mux, _ := setup(t)
+
+	mux.HandleFunc("/repos/o/r/notifications", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "PUT")
+		testHeader(t, r, "Content-Type", "application/json")
+		testBody(t, r, `{}`+"\n")
+
+		w.WriteHeader(http.StatusResetContent)
+	})
+
+	ctx := t.Context()
+	_, err := client.Activity.MarkRepositoryNotificationsRead(ctx, "o", "r", Timestamp{})
+	if err != nil {
+		t.Errorf("Activity.MarkRepositoryNotificationsRead returned error: %v", err)
+	}
+}
+
 func TestActivityService_GetThread(t *testing.T) {
 	t.Parallel()
 	client, mux, _ := setup(t)
diff --git a/github/repos_contents.go b/github/repos_contents.go
index 6090c8b9f92..73321e260d9 100644
--- a/github/repos_contents.go
+++ b/github/repos_contents.go
@@ -48,7 +48,7 @@ type RepositoryContent struct {
 // RepositoryContentResponse holds the parsed response from CreateFile, UpdateFile, and DeleteFile.
 type RepositoryContentResponse struct {
 	Content *RepositoryContent `json:"content,omitempty"`
-	Commit  `json:"commit,omitempty"`
+	Commit  `json:"commit"`
 }
 
 // RepositoryContentFileOptions specifies optional parameters for CreateFile, UpdateFile, and DeleteFile.