diff --git a/changelog/unreleased/fix-get-lock-header.md b/changelog/unreleased/fix-get-lock-header.md
new file mode 100644
index 0000000000..41227808d3
--- /dev/null
+++ b/changelog/unreleased/fix-get-lock-header.md
@@ -0,0 +1,5 @@
+Bugfix: Return wopi lock header in get lock response
+
+We fixed a bug where the wopi lock header was not returned in the get lock response. This is now fixed and the wopi validator tests are passing.
+
+https://github.com/owncloud/ocis/pull/10469
diff --git a/services/collaboration/pkg/connector/fileconnector.go b/services/collaboration/pkg/connector/fileconnector.go
index 073a18daf1..dd56887be6 100644
--- a/services/collaboration/pkg/connector/fileconnector.go
+++ b/services/collaboration/pkg/connector/fileconnector.go
@@ -147,8 +147,10 @@ func (f *FileConnector) GetLock(ctx context.Context) (*ConnectorResponse, error)
 			Str("StatusCode", resp.GetStatus().GetCode().String()).
 			Str("StatusMsg", resp.GetStatus().GetMessage()).
 			Msg("GetLock failed with unexpected status")
-		// TODO: Should we be more strict? There could be more causes for the failure
-		return NewResponse(404), nil
+		// Return 404 and the required header, even if it's empty
+		// https://docs.microsoft.com/en-us/microsoft-365/cloud-storage-partner-program/rest/files/getlock#response-headers
+		// This is needed to fulfill the requirements of online WOPI validator
+		return NewResponseWithLock(404, ""), nil
 	}
 
 	lockID := ""
diff --git a/services/collaboration/pkg/connector/fileconnector_test.go b/services/collaboration/pkg/connector/fileconnector_test.go
index b0f48586f5..c46e844e9a 100644
--- a/services/collaboration/pkg/connector/fileconnector_test.go
+++ b/services/collaboration/pkg/connector/fileconnector_test.go
@@ -113,7 +113,7 @@ var _ = Describe("FileConnector", func() {
 			response, err := fc.GetLock(ctx)
 			Expect(err).ToNot(HaveOccurred())
 			Expect(response.Status).To(Equal(404))
-			Expect(response.Headers).To(BeNil())
+			Expect(response.Headers[connector.HeaderWopiLock]).To(Equal(""))
 		})
 
 		It("Get lock success", func() {