diff --git a/modules/client/sync/device_one_time_keys_count.cc b/modules/client/sync/device_one_time_keys_count.cc
index 10251fa43..4ea65b597 100644
--- a/modules/client/sync/device_one_time_keys_count.cc
+++ b/modules/client/sync/device_one_time_keys_count.cc
@@ -33,11 +33,59 @@ ircd::m::sync::device_one_time_keys_count
 bool
 ircd::m::sync::device_one_time_keys_count_linear(data &data)
 {
-	return false;
+	if(!data.device_id)
+		return false;
+
+	return device_one_time_keys_count_polylog(data);
 }
 
 bool
 ircd::m::sync::device_one_time_keys_count_polylog(data &data)
 {
-	return false;
+	if(!data.device_id)
+		return false;
+
+	const auto event_idx
+	{
+		data.user_room.get(std::nothrow, "ircd.device_one_time_keys", data.device_id)
+	};
+
+	if(!apropos(data, event_idx))
+		return false;
+
+	std::map<string_view, long, std::less<>> counts;
+	m::device::get(data.user, data.device_id, "one_time_keys", [&counts]
+	(const string_view &one_time_keys)
+	{
+		if(json::type(one_time_keys) != json::OBJECT)
+			return;
+
+		for(const auto &[ident_, object] : json::object(one_time_keys))
+		{
+			const auto &[algorithm, ident]
+			{
+				split(ident_, ':')
+			};
+
+			auto it(counts.lower_bound(algorithm));
+			if(it == end(counts) || it->first != algorithm)
+				it = counts.emplace_hint(it, algorithm, 0L);
+
+			auto &count(it->second);
+			++count;
+		}
+	});
+
+	json::stack::object one_time_keys_count
+	{
+		*data.out, "device_one_time_keys_count"
+	};
+
+	for(const auto &[algorithm, count] : counts)
+		json::stack::member
+		{
+			one_time_keys_count, algorithm, json::value{count}
+		};
+
+	return true;
 }