diff --git a/src/base/bittorrent/portforwarderimpl.cpp b/src/base/bittorrent/portforwarderimpl.cpp
index 738d473a8..cff7dedac 100644
--- a/src/base/bittorrent/portforwarderimpl.cpp
+++ b/src/base/bittorrent/portforwarderimpl.cpp
@@ -30,8 +30,6 @@
 
 #include <libtorrent/session.hpp>
 
-#include <QDebug>
-
 #include "base/logger.h"
 
 PortForwarderImpl::PortForwarderImpl(lt::session *provider, QObject *parent)
@@ -55,61 +53,70 @@ bool PortForwarderImpl::isEnabled() const
 
 void PortForwarderImpl::setEnabled(const bool enabled)
 {
-    if (m_storeActive != enabled)
-    {
-        if (enabled)
-            start();
-        else
-            stop();
+    if (m_storeActive == enabled)
+        return;
 
-        m_storeActive = enabled;
-    }
+    if (enabled)
+        start();
+    else
+        stop();
+    m_storeActive = enabled;
 }
 
 void PortForwarderImpl::addPort(const quint16 port)
 {
-    if (!m_mappedPorts.contains(port))
-    {
+    if (m_mappedPorts.contains(port))
+        return;
+
+    if (isEnabled())
+        m_mappedPorts.insert(port, m_provider->add_port_mapping(lt::session::tcp, port, port));
+    else
         m_mappedPorts.insert(port, {});
-        if (isEnabled())
-            m_mappedPorts[port] = {m_provider->add_port_mapping(lt::session::tcp, port, port)};
-    }
 }
 
 void PortForwarderImpl::deletePort(const quint16 port)
 {
-    if (m_mappedPorts.contains(port))
+    const auto iter = m_mappedPorts.find(port);
+    if (iter == m_mappedPorts.end())
+        return;
+
+    if (isEnabled())
     {
-        if (isEnabled())
-        {
-            for (const lt::port_mapping_t &portMapping : m_mappedPorts[port])
+        for (const lt::port_mapping_t &portMapping : *iter)
             m_provider->delete_port_mapping(portMapping);
-        }
-        m_mappedPorts.remove(port);
     }
+
+    m_mappedPorts.erase(iter);
 }
 
 void PortForwarderImpl::start()
 {
-    qDebug("Enabling UPnP / NAT-PMP");
     lt::settings_pack settingsPack = m_provider->get_settings();
     settingsPack.set_bool(lt::settings_pack::enable_upnp, true);
     settingsPack.set_bool(lt::settings_pack::enable_natpmp, true);
     m_provider->apply_settings(settingsPack);
-    for (auto i = m_mappedPorts.begin(); i != m_mappedPorts.end(); ++i)
+
+    for (auto iter = m_mappedPorts.begin(); iter != m_mappedPorts.end(); ++iter)
     {
-        // quint16 port = i.key();
-        i.value() = {m_provider->add_port_mapping(lt::session::tcp, i.key(), i.key())};
+        Q_ASSERT(iter.value().empty());
+
+        const quint16 port = iter.key();
+        iter.value() = m_provider->add_port_mapping(lt::session::tcp, port, port);
     }
+
     LogMsg(tr("UPnP/NAT-PMP support: ON"), Log::INFO);
 }
 
 void PortForwarderImpl::stop()
 {
-    qDebug("Disabling UPnP / NAT-PMP");
     lt::settings_pack settingsPack = m_provider->get_settings();
     settingsPack.set_bool(lt::settings_pack::enable_upnp, false);
     settingsPack.set_bool(lt::settings_pack::enable_natpmp, false);
     m_provider->apply_settings(settingsPack);
+
+    // don't clear m_mappedPorts so a later `start()` call can restore the port forwarding
+    for (auto iter = m_mappedPorts.begin(); iter != m_mappedPorts.end(); ++iter)
+        iter.value().clear();
+
     LogMsg(tr("UPnP/NAT-PMP support: OFF"), Log::INFO);
 }
diff --git a/src/base/bittorrent/portforwarderimpl.h b/src/base/bittorrent/portforwarderimpl.h
index 5d04f86fe..dee74ed1c 100644
--- a/src/base/bittorrent/portforwarderimpl.h
+++ b/src/base/bittorrent/portforwarderimpl.h
@@ -58,6 +58,6 @@ private:
     void stop();
 
     CachedSettingValue<bool> m_storeActive;
-    lt::session *m_provider = nullptr;
+    lt::session *const m_provider = nullptr;
     QHash<quint16, std::vector<lt::port_mapping_t>> m_mappedPorts;
 };
diff --git a/src/base/bittorrent/sessionimpl.cpp b/src/base/bittorrent/sessionimpl.cpp
index 9316e9621..abdb1e03c 100644
--- a/src/base/bittorrent/sessionimpl.cpp
+++ b/src/base/bittorrent/sessionimpl.cpp
@@ -578,6 +578,29 @@ SessionImpl::SessionImpl(QObject *parent)
     prepareStartup();
 }
 
+SessionImpl::~SessionImpl()
+{
+    // Do some bittorrent related saving
+    // After this, (ideally) no more important alerts will be generated/handled
+    saveResumeData();
+
+    saveStatistics();
+
+    // We must delete FilterParserThread
+    // before we delete lt::session
+    delete m_filterParser;
+
+    // We must delete PortForwarderImpl before
+    // we delete lt::session
+    delete Net::PortForwarder::instance();
+
+    qDebug("Deleting the session");
+    delete m_nativeSession;
+
+    m_ioThread->quit();
+    m_ioThread->wait();
+}
+
 bool SessionImpl::isDHTEnabled() const
 {
     return m_isDHTEnabled;
@@ -1028,30 +1051,6 @@ void SessionImpl::setGlobalMaxSeedingMinutes(int minutes)
     }
 }
 
-// Main destructor
-SessionImpl::~SessionImpl()
-{
-    // Do some bittorrent related saving
-    // After this, (ideally) no more important alerts will be generated/handled
-    saveResumeData();
-
-    saveStatistics();
-
-    // We must delete FilterParserThread
-    // before we delete lt::session
-    delete m_filterParser;
-
-    // We must delete PortForwarderImpl before
-    // we delete lt::session
-    delete Net::PortForwarder::instance();
-
-    qDebug("Deleting the session");
-    delete m_nativeSession;
-
-    m_ioThread->quit();
-    m_ioThread->wait();
-}
-
 void SessionImpl::adjustLimits()
 {
     if (isQueueingSystemEnabled())