diff --git a/package.json b/package.json
index 264f309619..f6e9f8b7a1 100644
--- a/package.json
+++ b/package.json
@@ -60,7 +60,8 @@
     "err-code": "^1.1.2",
     "length-prefixed-stream": "^1.6.0",
     "protons": "^1.0.1",
-    "pull-pushable": "^2.2.0"
+    "pull-pushable": "^2.2.0",
+    "time-cache": "^0.3.0"
   },
   "contributors": [
     "Vasco Santos <vasco.santos@moxy.studio>"
diff --git a/src/index.js b/src/index.js
index a51c68ae7f..c2f5a3aa2e 100644
--- a/src/index.js
+++ b/src/index.js
@@ -4,7 +4,7 @@ const EventEmitter = require('events')
 const pull = require('pull-stream/pull')
 const empty = require('pull-stream/sources/empty')
 const asyncEach = require('async/each')
-
+const TimeCache = require('time-cache')
 const debug = require('debug')
 const errcode = require('err-code')
 
@@ -31,6 +31,20 @@ class PubsubBaseProtocol extends EventEmitter {
     this.multicodec = multicodec
     this.libp2p = libp2p
     this.started = false
+    
+    /**
+     * Map of topics to which peers are subscribed to
+     *
+     * @type {Map<string, Peer>}
+     */
+    this.topics = new Map()
+
+    /**
+     * Cache of seen messages
+     *
+     * @type {TimeCache}
+     */
+    this.seenCache = new TimeCache()
 
     /**
      * Map of peers.