diff --git a/include/ircd/m/room/members.h b/include/ircd/m/room/members.h
index 7dc6a3a33..31fe49fce 100644
--- a/include/ircd/m/room/members.h
+++ b/include/ircd/m/room/members.h
@@ -11,6 +11,11 @@
 #pragma once
 #define HAVE_IRCD_M_ROOM_MEMBERS_H
 
+namespace ircd::m
+{
+	constexpr size_t MEMBERSHIP_MAX_SIZE {16};
+}
+
 /// Interface to the members of a room.
 ///
 /// This interface focuses specifically on room membership and its routines
diff --git a/modules/client/rooms/forget.cc b/modules/client/rooms/forget.cc
index 1dfcc0b8c..b1f02e96c 100644
--- a/modules/client/rooms/forget.cc
+++ b/modules/client/rooms/forget.cc
@@ -39,13 +39,13 @@ post__forget(client &client,
 			string_view{room_id}
 		};
 
-	char room_membuf[32];
+	char room_membuf[m::MEMBERSHIP_MAX_SIZE];
 	const string_view &room_membership
 	{
 		room.membership(room_membuf, request.user_id)
 	};
 
-	char user_membuf[32];
+	char user_membuf[m::MEMBERSHIP_MAX_SIZE];
 	string_view user_membership;
 	m::get(std::nothrow, event_idx, "content", [&user_membuf, &user_membership]
 	(const json::object &content)
diff --git a/modules/client/rooms/initialsync.cc b/modules/client/rooms/initialsync.cc
index c6471aaad..4f72ec2bd 100644
--- a/modules/client/rooms/initialsync.cc
+++ b/modules/client/rooms/initialsync.cc
@@ -90,7 +90,7 @@ get__initialsync_local(client &client,
                        const m::user &user,
                        json::stack::object &out)
 {
-	char membership_buf[32];
+	char membership_buf[m::MEMBERSHIP_MAX_SIZE];
 	json::stack::member
 	{
 		out, "membership", room.membership(membership_buf, request.user_id)
diff --git a/modules/client/sync/rooms.cc b/modules/client/sync/rooms.cc
index 7a7b1ec91..660daea23 100644
--- a/modules/client/sync/rooms.cc
+++ b/modules/client/sync/rooms.cc
@@ -53,7 +53,7 @@ ircd::m::sync::rooms_linear(data &data)
 		data.room, &room
 	};
 
-	char membuf[32];
+	char membuf[MEMBERSHIP_MAX_SIZE];
 	const string_view &membership
 	{
 		data.room?
@@ -196,7 +196,7 @@ ircd::m::sync::_rooms_polylog(data &data,
 		}
 
 		#if defined(RB_DEBUG)
-		thread_local char tmbuf[32];
+		thread_local char tmbuf[MEMBERSHIP_MAX_SIZE];
 		if(data.stats && rooms.stats_debug) log::debug
 		{
 			log, "polylog %s %s %s in %s",
diff --git a/modules/client/sync/rooms/account_data.cc b/modules/client/sync/rooms/account_data.cc
index 659a0bbd7..58f9a2b75 100644
--- a/modules/client/sync/rooms/account_data.cc
+++ b/modules/client/sync/rooms/account_data.cc
@@ -88,7 +88,7 @@ ircd::m::sync::room_account_data_linear_events(data &data,
 		lstrip(json::get<"type"_>(event), type.first)
 	};
 
-	char membuf[32];
+	char membuf[MEMBERSHIP_MAX_SIZE];
 	const auto membership
 	{
 		room.membership(membuf, data.user)
@@ -150,7 +150,7 @@ ircd::m::sync::room_account_data_linear_tags(data &data,
 		lstrip(json::get<"type"_>(event), type.first)
 	};
 
-	char membuf[32];
+	char membuf[MEMBERSHIP_MAX_SIZE];
 	const auto membership
 	{
 		room.membership(membuf, data.user)
diff --git a/modules/federation/make_leave.cc b/modules/federation/make_leave.cc
index 10c283db4..c74ea6d55 100644
--- a/modules/federation/make_leave.cc
+++ b/modules/federation/make_leave.cc
@@ -72,7 +72,7 @@ get__make_leave(client &client,
 		room_id
 	};
 
-	char membuf[32];
+	char membuf[m::MEMBERSHIP_MAX_SIZE];
 	const string_view membership
 	{
 		room.membership(membuf, user_id)
diff --git a/modules/m_room_history_visibility.cc b/modules/m_room_history_visibility.cc
index 3675ebb7c..f4001b5d8 100644
--- a/modules/m_room_history_visibility.cc
+++ b/modules/m_room_history_visibility.cc
@@ -22,7 +22,7 @@ _visible_(const m::event &event,
           const m::room &room,
           const string_view &history_visibility)
 {
-	char membership_buf[32];
+	char membership_buf[m::MEMBERSHIP_MAX_SIZE];
 	string_view membership
 	{
 		room.membership(membership_buf, user_id)