diff --git a/dlls/wsdapi/soap.c b/dlls/wsdapi/soap.c
index 06d0129b13d..77793178507 100644
--- a/dlls/wsdapi/soap.c
+++ b/dlls/wsdapi/soap.c
@@ -71,6 +71,7 @@ static const WCHAR relatesToString[] = { 'R','e','l','a','t','e','s','T','o', 0
 static const WCHAR appSequenceString[] = { 'A','p','p','S','e','q','u','e','n','c','e', 0 };
 static const WCHAR instanceIdString[] = { 'I','n','s','t','a','n','c','e','I','d', 0 };
 static const WCHAR messageNumberString[] = { 'M','e','s','s','a','g','e','N','u','m','b','e','r', 0 };
+static const WCHAR sequenceIdString[] = { 'S','e','q','u','e','n','c','e','I','d', 0 };
 static const WCHAR emptyString[] = { 0 };
 
 struct discovered_namespace
@@ -437,6 +438,25 @@ static BOOL add_ulonglong_attribute(IWSDXMLContext *xml_context, WSDXML_ELEMENT
     return TRUE;
 }
 
+static BOOL add_string_attribute(IWSDXMLContext *xml_context, WSDXML_ELEMENT *parent, LPCWSTR ns_uri, LPCWSTR name,
+    LPCWSTR value)
+{
+    WSDXML_ATTRIBUTE *attribute = add_attribute(xml_context, parent, ns_uri, name);
+
+    if (attribute == NULL)
+        return FALSE;
+
+    attribute->Value = duplicate_string(attribute, value);
+
+    if (attribute->Value == NULL)
+    {
+        remove_attribute(parent, attribute);
+        return FALSE;
+    }
+
+    return TRUE;
+}
+
 static BOOL add_discovered_namespace(struct list *namespaces, WSDXML_NAMESPACE *discovered_ns)
 {
     struct discovered_namespace *ns;
@@ -499,12 +519,17 @@ static WSDXML_ELEMENT *create_soap_header_xml_elements(IWSDXMLContext *xml_conte
     if (!add_ulonglong_attribute(xml_context, app_sequence_element, NULL, instanceIdString, min(UINT_MAX,
         header->AppSequence->InstanceId))) goto cleanup;
 
+    /* SequenceID attribute */
+    if (header->AppSequence->SequenceId != NULL)
+    {
+        if (!add_string_attribute(xml_context, app_sequence_element, NULL, sequenceIdString, header->AppSequence->SequenceId))
+            goto cleanup;
+    }
+
     /* MessageNumber attribute */
     if (!add_ulonglong_attribute(xml_context, app_sequence_element, NULL, messageNumberString, min(UINT_MAX,
         header->AppSequence->MessageNumber))) goto cleanup;
 
-    /* TODO: SequenceID attribute */
-
     /* </d:AppSequence> */
 
     /* TODO: Write any headers */
diff --git a/dlls/wsdapi/tests/discovery.c b/dlls/wsdapi/tests/discovery.c
index 1fa96b77092..1c7619d5e6e 100644
--- a/dlls/wsdapi/tests/discovery.c
+++ b/dlls/wsdapi/tests/discovery.c
@@ -39,6 +39,7 @@
 #define SEND_PORT           "3702"
 
 static const char *publisherId = "urn:uuid:3AE5617D-790F-408A-9374-359A77F924A3";
+static const char *sequenceId = "urn:uuid:b14de351-72fc-4453-96f9-e58b0c9faf38";
 
 #define MAX_CACHED_MESSAGES     5
 #define MAX_LISTENING_THREADS  20
@@ -501,8 +502,8 @@ static void Publish_tests(void)
     IWSDiscoveryPublisher *publisher = NULL;
     IWSDiscoveryPublisherNotify *sink1 = NULL, *sink2 = NULL;
     IWSDiscoveryPublisherNotifyImpl *sink1Impl = NULL, *sink2Impl = NULL;
-    char endpointReferenceString[MAX_PATH];
-    LPWSTR publisherIdW = NULL;
+    char endpointReferenceString[MAX_PATH], app_sequence_string[MAX_PATH];
+    LPWSTR publisherIdW = NULL, sequenceIdW = NULL;
     messageStorage *msgStorage;
     WSADATA wsaData;
     BOOL messageOK, hello_message_seen = FALSE, endpoint_reference_seen = FALSE, app_sequence_seen = FALSE;
@@ -557,6 +558,9 @@ static void Publish_tests(void)
     publisherIdW = utf8_to_wide(publisherId);
     if (publisherIdW == NULL) goto after_publish_test;
 
+    sequenceIdW = utf8_to_wide(sequenceId);
+    if (sequenceIdW == NULL) goto after_publish_test;
+
     msgStorage = heap_alloc_zero(sizeof(messageStorage));
     if (msgStorage == NULL) goto after_publish_test;
 
@@ -570,7 +574,7 @@ static void Publish_tests(void)
     ok(ret == TRUE, "Unable to listen on IPv4 addresses (ret == %d)\n", ret);
 
     /* Publish the service */
-    rc = IWSDiscoveryPublisher_Publish(publisher, publisherIdW, 1, 1, 1, NULL, NULL, NULL, NULL);
+    rc = IWSDiscoveryPublisher_Publish(publisher, publisherIdW, 1, 1, 1, sequenceIdW, NULL, NULL, NULL);
     ok(rc == S_OK, "Publish failed: %08x\n", rc);
 
     /* Wait up to 2 seconds for messages to be received */
@@ -587,6 +591,8 @@ static void Publish_tests(void)
     ok(msgStorage->messageCount >= 1, "No messages received\n");
 
     sprintf(endpointReferenceString, "<wsa:EndpointReference><wsa:Address>%s</wsa:Address></wsa:EndpointReference>", publisherId);
+    sprintf(app_sequence_string, "<wsd:AppSequence InstanceId=\"1\" SequenceId=\"%s\" MessageNumber=\"1\"></wsd:AppSequence>",
+        sequenceId);
 
     messageOK = FALSE;
 
@@ -598,7 +604,7 @@ static void Publish_tests(void)
 
         hello_message_seen = (strstr(msg, "<wsa:Action>http://schemas.xmlsoap.org/ws/2005/04/discovery/Hello</wsa:Action>") != NULL);
         endpoint_reference_seen = (strstr(msg, endpointReferenceString) != NULL);
-        app_sequence_seen = (strstr(msg, "<wsd:AppSequence InstanceId=\"1\" MessageNumber=\"1\"></wsd:AppSequence>") != NULL);
+        app_sequence_seen = (strstr(msg, app_sequence_string) != NULL);
         metadata_version_seen = (strstr(msg, "<wsd:MetadataVersion>1</wsd:MetadataVersion>") != NULL);
         messageOK = hello_message_seen && endpoint_reference_seen && app_sequence_seen && metadata_version_seen;
 
@@ -621,6 +627,7 @@ static void Publish_tests(void)
 after_publish_test:
 
     if (publisherIdW != NULL) heap_free(publisherIdW);
+    if (sequenceIdW != NULL) heap_free(sequenceIdW);
 
     ref = IWSDiscoveryPublisher_Release(publisher);
     ok(ref == 0, "IWSDiscoveryPublisher_Release() has %d references, should have 0\n", ref);