diff --git a/libretroshare/src/retroshare/rsgxsforums.h b/libretroshare/src/retroshare/rsgxsforums.h
index 1c95bed87..19a80b011 100644
--- a/libretroshare/src/retroshare/rsgxsforums.h
+++ b/libretroshare/src/retroshare/rsgxsforums.h
@@ -59,25 +59,17 @@ struct RsGxsForumGroup : RsSerializable
 	RsGroupMetaData mMeta;
 	std::string mDescription;
 
-	/* What's below is optional, and handled by the serialiser
-	 * TODO: run away from TLV old serializables as those types are opaque to
-	 *	JSON API! */
+	/* TODO: run away from TLV old serializables as those types are opaque to
+	 * JSON API! */
 	RsTlvGxsIdSet mAdminList;
 	RsTlvGxsMsgIdSet mPinnedPosts;
 
 	/// @see RsSerializable
 	virtual void serial_process( RsGenericSerializer::SerializeJob j,
-	                             RsGenericSerializer::SerializeContext& ctx )
-	{
-		RS_SERIAL_PROCESS(mMeta);
-		RS_SERIAL_PROCESS(mDescription);
-		RS_SERIAL_PROCESS(mAdminList);
-		RS_SERIAL_PROCESS(mPinnedPosts);
-	}
+	                             RsGenericSerializer::SerializeContext& ctx );
 
-    // utility functions
-
-    bool canEditPosts(const RsGxsId& id) const { return mAdminList.ids.find(id) != mAdminList.ids.end() || id == mMeta.mAuthorId; }
+	/// utility functions
+	bool canEditPosts(const RsGxsId& id) const;
 };
 
 struct RsGxsForumMsg : RsSerializable
@@ -203,4 +195,3 @@ public:
 	RS_DEPRECATED_FOR(editForum)
 	virtual bool updateGroup(uint32_t &token, RsGxsForumGroup &group) = 0;
 };
-
diff --git a/libretroshare/src/services/p3gxsforums.cc b/libretroshare/src/services/p3gxsforums.cc
index 07f91e33f..e82a5a5e0 100644
--- a/libretroshare/src/services/p3gxsforums.cc
+++ b/libretroshare/src/services/p3gxsforums.cc
@@ -813,3 +813,34 @@ void p3GxsForums::handle_event(uint32_t event_type, const std::string &/*elabel*
 			break;
 	}
 }
+
+void RsGxsForumGroup::serial_process(
+        RsGenericSerializer::SerializeJob j,
+        RsGenericSerializer::SerializeContext& ctx )
+{
+	RS_SERIAL_PROCESS(mMeta);
+	RS_SERIAL_PROCESS(mDescription);
+
+	/* Work around to have usable JSON API, without breaking binary
+	 * serialization retrocompatibility */
+	switch (j)
+	{
+	case RsGenericSerializer::TO_JSON: // fallthrough
+	case RsGenericSerializer::FROM_JSON:
+		RsTypeSerializer::serial_process( j, ctx,
+		                                  mAdminList.ids, "mAdminList" );
+		RsTypeSerializer::serial_process( j, ctx,
+		                                  mPinnedPosts.ids, "mPinnedPosts" );
+		break;
+	default:
+		RS_SERIAL_PROCESS(mAdminList);
+		RS_SERIAL_PROCESS(mPinnedPosts);
+	}
+}
+
+bool RsGxsForumGroup::canEditPosts(const RsGxsId& id) const
+{
+	return mAdminList.ids.find(id) != mAdminList.ids.end() ||
+	        id == mMeta.mAuthorId;
+}
+