diff --git a/libwhisper/WhisperHost.cpp b/libwhisper/WhisperHost.cpp
index 1a47a56d1..150d5cd63 100644
--- a/libwhisper/WhisperHost.cpp
+++ b/libwhisper/WhisperHost.cpp
@@ -94,14 +94,16 @@ unsigned WhisperHost::installWatch(shh::Topics const& _t)
 
 	DEV_GUARDED(m_filterLock)
 	{
-		if (!m_filters.count(h))
+		auto it = m_filters.find(h);
+		if (m_filters.end() == it)
 			m_filters.insert(make_pair(h, f));
+		else
+			it->second.refCount++;
 
+		m_bloom.addRaw(f.filter.exportBloom());
 		ret = m_watches.size() ? m_watches.rbegin()->first + 1 : 0;
 		m_watches[ret] = ClientWatch(h);
 		cwatshh << "+++" << ret << h;
-
-		m_bloom.addRaw(f.filter.exportBloom());
 	}
 
 	noteAdvertiseTopicsOfInterest();
@@ -138,16 +140,16 @@ void WhisperHost::uninstallWatch(unsigned _i)
 		auto it = m_watches.find(_i);
 		if (it == m_watches.end())
 			return;
+
 		auto id = it->second.id;
 		m_watches.erase(it);
 
 		auto fit = m_filters.find(id);
 		if (fit != m_filters.end())
 		{
+			m_bloom.removeRaw(fit->second.filter.exportBloom());
 			if (!--fit->second.refCount)
 				m_filters.erase(fit);
-
-			m_bloom.removeRaw(fit->second.filter.exportBloom());
 		}
 	}
 
diff --git a/libwhisper/WhisperPeer.cpp b/libwhisper/WhisperPeer.cpp
index 665364f49..1f48468df 100644
--- a/libwhisper/WhisperPeer.cpp
+++ b/libwhisper/WhisperPeer.cpp
@@ -58,7 +58,10 @@ bool WhisperPeer::interpret(unsigned _id, RLP const& _r)
 			disable("Invalid protocol version.");
 
 		for (auto const& m: host()->all())
+		{
+			Guard l(x_unseen);
 			m_unseen.insert(make_pair(0, m.first));
+		}
 
 		if (session()->id() < host()->host()->id())
 			sendMessages();
diff --git a/test/libwhisper/whisperTopic.cpp b/test/libwhisper/whisperTopic.cpp
index a152f756e..47d17503c 100644
--- a/test/libwhisper/whisperTopic.cpp
+++ b/test/libwhisper/whisperTopic.cpp
@@ -320,7 +320,7 @@ BOOST_AUTO_TEST_CASE(topicAdvertising)
 	Host host2("second", NetworkPreferences("127.0.0.1", 30305, false));
 	host2.setIdealPeerCount(1);
 	auto whost2 = host2.registerCapability(new WhisperHost());
-	whost2->installWatch(BuildTopicMask("test2"));
+	unsigned w2 = whost2->installWatch(BuildTopicMask("test2"));
 
 	host2.start();
 	while (!host2.haveNetwork())
@@ -354,7 +354,7 @@ BOOST_AUTO_TEST_CASE(topicAdvertising)
 	BOOST_REQUIRE(bf1);
 	BOOST_REQUIRE(!whost1->bloom());
 
-	whost1->installWatch(BuildTopicMask("test1"));
+	unsigned w1 = whost1->installWatch(BuildTopicMask("test1"));
 
 	for (int i = 0; i < 600; ++i)
 	{
@@ -372,6 +372,16 @@ BOOST_AUTO_TEST_CASE(topicAdvertising)
 	bf1 = whost1->bloom();
 	BOOST_REQUIRE_EQUAL(bf1, bf2);
 	BOOST_REQUIRE(bf1);
+
+	unsigned random = 0xC0FFEE;
+	whost1->uninstallWatch(w1);
+	whost1->uninstallWatch(random);
+	whost1->uninstallWatch(w1);
+	whost1->uninstallWatch(random);
+	whost2->uninstallWatch(random);
+	whost2->uninstallWatch(w2);
+	whost2->uninstallWatch(random);
+	whost2->uninstallWatch(w2);
 }
 
 BOOST_AUTO_TEST_SUITE_END()