diff --git a/src/ssb.c b/src/ssb.c
index 76fe3419..e7a977fd 100644
--- a/src/ssb.c
+++ b/src/ssb.c
@@ -1784,18 +1784,28 @@ static bool _tf_ssb_connection_box_stream_recv(tf_ssb_connection_t* connection)
 	return true;
 }
 
-JSValue tf_ssb_sign_message(tf_ssb_t* ssb, const char* author, const uint8_t* private_key, JSValue message)
+JSValue tf_ssb_sign_message(tf_ssb_t* ssb, const char* author, const uint8_t* private_key, JSValue message, const char* previous_id, int64_t previous_sequence)
 {
-	char previous_id[crypto_hash_sha256_BYTES * 2];
-	int64_t previous_sequence = 0;
-	bool have_previous = tf_ssb_db_get_latest_message_by_author(ssb, author, &previous_sequence, previous_id, sizeof(previous_id));
+	char actual_previous_id[crypto_hash_sha256_BYTES * 2];
+	int64_t actual_previous_sequence = 0;
+	bool have_previous = false;
+	if (previous_id)
+	{
+		have_previous = *previous_id && previous_sequence > 0;
+		snprintf(actual_previous_id, sizeof(actual_previous_id), "%s", previous_id);
+		actual_previous_sequence = previous_sequence;
+	}
+	else
+	{
+		have_previous = tf_ssb_db_get_latest_message_by_author(ssb, author, &actual_previous_sequence, actual_previous_id, sizeof(actual_previous_id));
+	}
 
 	JSContext* context = ssb->context;
 	JSValue root = JS_NewObject(context);
 
-	JS_SetPropertyStr(context, root, "previous", have_previous ? JS_NewString(context, previous_id) : JS_NULL);
+	JS_SetPropertyStr(context, root, "previous", have_previous ? JS_NewString(context, actual_previous_id) : JS_NULL);
 	JS_SetPropertyStr(context, root, "author", JS_NewString(context, author));
-	JS_SetPropertyStr(context, root, "sequence", JS_NewInt64(context, previous_sequence + 1));
+	JS_SetPropertyStr(context, root, "sequence", JS_NewInt64(context, actual_previous_sequence + 1));
 
 	int64_t now = (int64_t)time(NULL);
 	JS_SetPropertyStr(context, root, "timestamp", JS_NewInt64(context, now * 1000LL));
diff --git a/src/ssb.h b/src/ssb.h
index 2e7720dd..4cfbe956 100644
--- a/src/ssb.h
+++ b/src/ssb.h
@@ -278,9 +278,11 @@ void tf_ssb_run(tf_ssb_t* ssb);
 ** @param author The author's public key.
 ** @param private_key The author's private key.
 ** @param message The message to sign.
+** @param previous_id The ID of the previous message in the feed.  Optional.
+** @param previous_sequence The sequence number of the previous message in the feed.  Optional.
 ** @return The signed message.
 */
-JSValue tf_ssb_sign_message(tf_ssb_t* ssb, const char* author, const uint8_t* private_key, JSValue message);
+JSValue tf_ssb_sign_message(tf_ssb_t* ssb, const char* author, const uint8_t* private_key, JSValue message, const char* previous_id, int64_t previous_sequence);
 
 /**
 ** Get the server's identity.
diff --git a/src/ssb.js.c b/src/ssb.js.c
index bf5edc80..e8a54797 100644
--- a/src/ssb.js.c
+++ b/src/ssb.js.c
@@ -663,8 +663,15 @@ static JSValue _tf_ssb_getIdentityInfo(JSContext* context, JSValueConst this_val
 
 typedef struct _append_message_t
 {
+	char id[k_id_base64_len];
+	uint8_t private_key[crypto_sign_SECRETKEYBYTES];
+	bool got_private_key;
+	char previous_id[512];
+	int64_t previous_sequence;
 	JSContext* context;
 	JSValue promise[2];
+	JSValue message;
+	char user[];
 } append_message_t;
 
 static void _tf_ssb_appendMessage_finish(append_message_t* async, bool success, JSValue result)
@@ -672,6 +679,7 @@ static void _tf_ssb_appendMessage_finish(append_message_t* async, bool success,
 	JSValue error = JS_Call(async->context, success ? async->promise[0] : async->promise[1], JS_UNDEFINED, 1, &result);
 	tf_util_report_error(async->context, error);
 	JS_FreeValue(async->context, error);
+	JS_FreeValue(async->context, async->message);
 	JS_FreeValue(async->context, async->promise[0]);
 	JS_FreeValue(async->context, async->promise[1]);
 	tf_free(async);
@@ -688,35 +696,50 @@ static void _tf_ssb_appendMessageWithIdentity_callback(const char* id, bool veri
 	_tf_ssb_appendMessage_finish(async, verified, result);
 }
 
-static JSValue _tf_ssb_appendMessageWithIdentity(JSContext* context, JSValueConst this_val, int argc, JSValueConst* argv)
+static void _tf_ssb_append_message_with_identity_get_key_work(tf_ssb_t* ssb, void* user_data)
 {
-	append_message_t* async = tf_malloc(sizeof(append_message_t));
-	*async = (append_message_t) { .context = context };
-	JSValue result = JS_NewPromiseCapability(context, async->promise);
+	append_message_t* work = user_data;
+	work->got_private_key = tf_ssb_db_identity_get_private_key(ssb, work->user, work->id, work->private_key, sizeof(work->private_key));
+	tf_ssb_db_get_latest_message_by_author(ssb, work->id, &work->previous_sequence, work->previous_id, sizeof(work->previous_id));
+}
 
-	tf_ssb_t* ssb = JS_GetOpaque(this_val, _tf_ssb_classId);
-	if (ssb)
+static void _tf_ssb_append_message_with_identity_get_key_after_work(tf_ssb_t* ssb, int status, void* user_data)
+{
+	append_message_t* work = user_data;
+	if (work->got_private_key)
 	{
-		const char* user = JS_ToCString(context, argv[0]);
-		const char* id = JS_ToCString(context, argv[1]);
-		uint8_t private_key[crypto_sign_SECRETKEYBYTES];
-		if (tf_ssb_db_identity_get_private_key(ssb, user, id, private_key, sizeof(private_key)))
-		{
-			JSValue signed_message = tf_ssb_sign_message(ssb, id, private_key, argv[2]);
-			tf_ssb_verify_strip_and_store_message(ssb, signed_message, _tf_ssb_appendMessageWithIdentity_callback, async);
-			JS_FreeValue(context, signed_message);
-		}
-		else
-		{
-			_tf_ssb_appendMessage_finish(async, false, JS_ThrowInternalError(context, "Unable to get private key for user %s with identity %s.", user, id));
-		}
-		JS_FreeCString(context, id);
-		JS_FreeCString(context, user);
+		JSValue signed_message = tf_ssb_sign_message(ssb, work->id, work->private_key, work->message, work->previous_id, work->previous_sequence);
+		tf_ssb_verify_strip_and_store_message(ssb, signed_message, _tf_ssb_appendMessageWithIdentity_callback, work);
+		JS_FreeValue(work->context, signed_message);
 	}
 	else
 	{
-		_tf_ssb_appendMessage_finish(async, false, JS_ThrowInternalError(context, "No SSB instance."));
+		_tf_ssb_appendMessage_finish(work, false, JS_ThrowInternalError(work->context, "Unable to get private key for user %s with identity %s.", work->user, work->id));
 	}
+}
+
+static JSValue _tf_ssb_appendMessageWithIdentity(JSContext* context, JSValueConst this_val, int argc, JSValueConst* argv)
+{
+	tf_ssb_t* ssb = JS_GetOpaque(this_val, _tf_ssb_classId);
+	if (!ssb)
+	{
+		return JS_ThrowInternalError(context, "No SSB instance.");
+	}
+
+	size_t user_length = 0;
+	const char* user = JS_ToCStringLen(context, &user_length, argv[0]);
+	const char* id = JS_ToCString(context, argv[1]);
+
+	append_message_t* work = tf_malloc(sizeof(append_message_t) + user_length + 1);
+	*work = (append_message_t) { .context = context, .message = JS_DupValue(context, argv[2]) };
+	memcpy(work->user, user, user_length + 1);
+	snprintf(work->id, sizeof(work->id), "%s", id);
+
+	JS_FreeCString(context, id);
+	JS_FreeCString(context, user);
+
+	JSValue result = JS_NewPromiseCapability(context, work->promise);
+	tf_ssb_run_work(ssb, _tf_ssb_append_message_with_identity_get_key_work, _tf_ssb_append_message_with_identity_get_key_after_work, work);
 	return result;
 }
 
diff --git a/src/ssb.tests.c b/src/ssb.tests.c
index b47124e1..1c97c8b6 100644
--- a/src/ssb.tests.c
+++ b/src/ssb.tests.c
@@ -192,7 +192,7 @@ void tf_ssb_test_ssb(const tf_test_options_t* options)
 	JS_SetPropertyStr(context0, obj, "type", JS_NewString(context0, "post"));
 	JS_SetPropertyStr(context0, obj, "text", JS_NewString(context0, "Hello, world!"));
 	bool stored = false;
-	JSValue signed_message = tf_ssb_sign_message(ssb0, id0, priv0, obj);
+	JSValue signed_message = tf_ssb_sign_message(ssb0, id0, priv0, obj, NULL, 0);
 	tf_ssb_verify_strip_and_store_message(ssb0, signed_message, _message_stored, &stored);
 	JS_FreeValue(context0, signed_message);
 	_wait_stored(ssb0, &stored);
@@ -202,7 +202,7 @@ void tf_ssb_test_ssb(const tf_test_options_t* options)
 	JS_SetPropertyStr(context0, obj, "type", JS_NewString(context0, "post"));
 	JS_SetPropertyStr(context0, obj, "text", JS_NewString(context0, "First post."));
 	stored = false;
-	signed_message = tf_ssb_sign_message(ssb0, id0, priv0, obj);
+	signed_message = tf_ssb_sign_message(ssb0, id0, priv0, obj, NULL, 0);
 	tf_ssb_verify_strip_and_store_message(ssb0, signed_message, _message_stored, &stored);
 	JS_FreeValue(context0, signed_message);
 	_wait_stored(ssb0, &stored);
@@ -217,7 +217,7 @@ void tf_ssb_test_ssb(const tf_test_options_t* options)
 	JS_SetPropertyUint32(context0, mentions, 0, mention);
 	JS_SetPropertyStr(context0, obj, "mentions", mentions);
 	stored = false;
-	signed_message = tf_ssb_sign_message(ssb0, id0, priv0, obj);
+	signed_message = tf_ssb_sign_message(ssb0, id0, priv0, obj, NULL, 0);
 	tf_ssb_verify_strip_and_store_message(ssb0, signed_message, _message_stored, &stored);
 	JS_FreeValue(context0, signed_message);
 	_wait_stored(ssb0, &stored);
@@ -276,7 +276,7 @@ void tf_ssb_test_ssb(const tf_test_options_t* options)
 	JS_SetPropertyStr(context0, obj, "type", JS_NewString(context0, "post"));
 	JS_SetPropertyStr(context0, obj, "text", JS_NewString(context0, "Message to self."));
 	stored = false;
-	signed_message = tf_ssb_sign_message(ssb0, id0, priv0, obj);
+	signed_message = tf_ssb_sign_message(ssb0, id0, priv0, obj, NULL, 0);
 	tf_ssb_verify_strip_and_store_message(ssb0, signed_message, _message_stored, &stored);
 	JS_FreeValue(context0, signed_message);
 	_wait_stored(ssb0, &stored);
@@ -549,7 +549,7 @@ void tf_ssb_test_following(const tf_test_options_t* options)
 	JS_SetPropertyStr(context, message, "contact", JS_NewString(context, contact)); \
 	JS_SetPropertyStr(context, message, "following", follow ? JS_TRUE : JS_FALSE); \
 	JS_SetPropertyStr(context, message, "blocking", block ? JS_TRUE : JS_FALSE); \
-	signed_message = tf_ssb_sign_message(ssb0, id, priv, message); \
+	signed_message = tf_ssb_sign_message(ssb0, id, priv, message, NULL, 0); \
 	stored = false; \
 	tf_ssb_verify_strip_and_store_message(ssb0, signed_message, _message_stored, &stored); \
 	_wait_stored(ssb0, &stored); \
@@ -608,7 +608,7 @@ void tf_ssb_test_bench(const tf_test_options_t* options)
 	for (int i = 0; i < k_messages; i++)
 	{
 		bool stored = false;
-		JSValue signed_message = tf_ssb_sign_message(ssb0, id0, priv0, obj);
+		JSValue signed_message = tf_ssb_sign_message(ssb0, id0, priv0, obj, NULL, 0);
 		tf_ssb_verify_strip_and_store_message(ssb0, signed_message, _message_stored, &stored);
 		JS_FreeValue(tf_ssb_get_context(ssb0), signed_message);
 		_wait_stored(ssb0, &stored);