diff --git a/app/CMakeLists.txt b/app/CMakeLists.txt
index 6050fabfe..6f0395705 100644
--- a/app/CMakeLists.txt
+++ b/app/CMakeLists.txt
@@ -107,6 +107,7 @@ else()
     -Wall
     -Wextra
     -Wno-unused-parameter
+    -Wshadow
   )
 endif()
 
diff --git a/app/node/input.cpp b/app/node/input.cpp
index 3ec99b36f..d17656194 100644
--- a/app/node/input.cpp
+++ b/app/node/input.cpp
@@ -81,13 +81,15 @@ QString NodeInput::name()
 
 void NodeInput::Load(QXmlStreamReader *reader, XMLNodeData &xml_node_data, const QAtomicInt *cancelled)
 {
-  XMLAttributeLoop(reader, attr) {
-    if (cancelled && *cancelled) {
-      return;
-    }
+  {
+    XMLAttributeLoop(reader, attr) {
+      if (cancelled && *cancelled) {
+        return;
+      }
 
-    if (attr.name() == QStringLiteral("keyframing")) {
-      set_is_keyframing(attr.value() == QStringLiteral("1"));
+      if (attr.name() == QStringLiteral("keyframing")) {
+        set_is_keyframing(attr.value() == QStringLiteral("1"));
+      }
     }
   }
 
diff --git a/app/node/output/track/tracklist.cpp b/app/node/output/track/tracklist.cpp
index 67a19c91b..abe36e1e7 100644
--- a/app/node/output/track/tracklist.cpp
+++ b/app/node/output/track/tracklist.cpp
@@ -151,9 +151,9 @@ void TrackList::RemoveTrack()
 
 void TrackList::TrackConnected(NodeEdgePtr edge)
 {
-  int track_index = track_input_->IndexOfSubParameter(edge->input());
+  int input_index = track_input_->IndexOfSubParameter(edge->input());
 
-  Q_ASSERT(track_index >= 0);
+  Q_ASSERT(input_index >= 0);
 
   Node* connected_node = edge->output()->parentNode();
 
@@ -163,7 +163,7 @@ void TrackList::TrackConnected(NodeEdgePtr edge)
     {
       // Find "real" index
       TrackOutput* next = nullptr;
-      for (int i=track_index+1; i<track_input_->GetSize(); i++) {
+      for (int i=input_index+1; i<track_input_->GetSize(); i++) {
         Node* that_track = track_input_->At(i)->get_connected_node();
 
         if (that_track && that_track->IsTrack()) {
diff --git a/app/render/backend/opengl/openglproxy.cpp b/app/render/backend/opengl/openglproxy.cpp
index c96e52d7a..08aa8864c 100644
--- a/app/render/backend/opengl/openglproxy.cpp
+++ b/app/render/backend/opengl/openglproxy.cpp
@@ -276,21 +276,21 @@ QVariant OpenGLProxy::RunNodeAccelerated(const Node *node,
 
   shader->bind();
 
-  NodeValueMap::const_iterator i;
-  for (i=job.GetValues().constBegin(); i!=job.GetValues().constEnd(); i++) {
+  NodeValueMap::const_iterator it;
+  for (it=job.GetValues().constBegin(); it!=job.GetValues().constEnd(); it++) {
     // See if the shader has takes this parameter as an input
-    int variable_location = shader->uniformLocation(i.key()->id());
+    int variable_location = shader->uniformLocation(it.key()->id());
 
     if (variable_location == -1) {
       continue;
     }
 
     // This variable is used in the shader, let's set it
-    const QVariant& value = i.value().data();
+    const QVariant& value = it.value().data();
 
-    const NodeParam::DataType& data_type = (i.value().type() != NodeParam::kNone)
-        ? i.value().type()
-        : i.key()->data_type();
+    const NodeParam::DataType& data_type = (it.value().type() != NodeParam::kNone)
+        ? it.value().type()
+        : it.key()->data_type();
 
     switch (data_type) {
     case NodeInput::kInt:
@@ -300,7 +300,7 @@ QVariant OpenGLProxy::RunNodeAccelerated(const Node *node,
       shader->setUniformValue(variable_location, value.toFloat());
       break;
     case NodeInput::kVec2:
-      if (i.key()->IsArray()) {
+      if (it.key()->IsArray()) {
         QVector<NodeValue> nv = value.value< QVector<NodeValue> >();
         QVector<QVector2D> a(nv.size());
 
@@ -310,7 +310,7 @@ QVariant OpenGLProxy::RunNodeAccelerated(const Node *node,
 
         shader->setUniformValueArray(variable_location, a.constData(), a.size());
 
-        int count_location = shader->uniformLocation(QStringLiteral("%1_count").arg(i.key()->id()));
+        int count_location = shader->uniformLocation(QStringLiteral("%1_count").arg(it.key()->id()));
         if (count_location > -1) {
           shader->setUniformValue(count_location, a.size());
         }
@@ -354,7 +354,7 @@ QVariant OpenGLProxy::RunNodeAccelerated(const Node *node,
       shader->setUniformValue(variable_location, textures_to_bind.size());
 
       // If this texture binding is the iterative input, set it here
-      if (i.key() == job.GetIterativeInput()) {
+      if (it.key() == job.GetIterativeInput()) {
         iterative_input = textures_to_bind.size();
       }
 
@@ -362,7 +362,7 @@ QVariant OpenGLProxy::RunNodeAccelerated(const Node *node,
       textures_to_bind.append(tex_id);
 
       // Set enable flag if shader wants it
-      int enable_param_location = shader->uniformLocation(QStringLiteral("%1_enabled").arg(i.key()->id()));
+      int enable_param_location = shader->uniformLocation(QStringLiteral("%1_enabled").arg(it.key()->id()));
       if (enable_param_location > -1) {
         shader->setUniformValue(enable_param_location,
                                 tex_id > 0);
@@ -370,7 +370,7 @@ QVariant OpenGLProxy::RunNodeAccelerated(const Node *node,
 
       if (tex_id > 0) {
         // Set texture resolution if shader wants it
-        int res_param_location = shader->uniformLocation(QStringLiteral("%1_resolution").arg(i.key()->id()));
+        int res_param_location = shader->uniformLocation(QStringLiteral("%1_resolution").arg(it.key()->id()));
         if (res_param_location > -1) {
           shader->setUniformValue(res_param_location,
                                   static_cast<GLfloat>(texture->texture()->width() * texture->texture()->divider()),
diff --git a/app/render/backend/renderbackend.cpp b/app/render/backend/renderbackend.cpp
index df96c9efc..b9f90e5e4 100644
--- a/app/render/backend/renderbackend.cpp
+++ b/app/render/backend/renderbackend.cpp
@@ -115,13 +115,13 @@ void RenderBackend::ClearVideoQueue()
 
 QFuture<QVector<QByteArray> > RenderBackend::Hash(const QVector<rational> &times)
 {
-  return QtConcurrent::run(&pool_, [this](const QVector<rational> &times){
-    QVector<QByteArray> hashes(times.size());
+  return QtConcurrent::run(&pool_, [this](const QVector<rational> &t){
+    QVector<QByteArray> hashes(t.size());
 
     for (int i=0;i<hashes.size();i++) {
       hashes[i] = HashNode(copied_viewer_node_->texture_input()->get_connected_node(),
                            video_params_,
-                           times.at(i));
+                           t.at(i));
     }
 
     return hashes;
diff --git a/app/task/render/render.cpp b/app/task/render/render.cpp
index 133a6bf1d..f0da1ff54 100644
--- a/app/task/render/render.cpp
+++ b/app/task/render/render.cpp
@@ -93,12 +93,10 @@ void RenderTask::Render(const TimeRangeList& video_range,
   if (!video_range.isEmpty()) {
     QList<QByteArray> existing_hashes;
 
-    foreach (const TimeRange& r, video_range) {
-      total_length += r.length().toDouble();
-    }
-
     times = viewer_->video_frame_cache()->GetFrameListFromTimeRange(video_range);
 
+    total_length += video_frame_sz * times.size();
+
     QFuture<QVector<QByteArray> > hash_future = backend_.Hash(times);
     hashes = hash_future.result();
 
@@ -125,7 +123,7 @@ void RenderTask::Render(const TimeRangeList& video_range,
              || !download_futures.empty()
              || !audio_lookup_table.empty())) {
 
-    if (!frame_queue.empty()) {
+    if (!IsCancelled() && !frame_queue.empty()) {
       // Pop another frame off the frame queue
       const HashTimePair& p = frame_queue.front();
 
@@ -138,11 +136,14 @@ void RenderTask::Render(const TimeRangeList& video_range,
         bool hash_exists = false;
 
         if (use_disk_cache) {
-          bool hash_exists = (std::find(existing_hashes.begin(), existing_hashes.end(), p.hash) != existing_hashes.end());
+          // Check if this hash is in our "existing hashes" list
+          hash_exists = (std::find(existing_hashes.begin(), existing_hashes.end(), p.hash) != existing_hashes.end());
 
+          // If not, check if it's in the filesystem
           if (!hash_exists) {
             hash_exists = QFileInfo::exists(viewer_->video_frame_cache()->CachePathName(p.hash));
 
+            // If so, add it to the list so we don't have to check the filesystem again later
             if (hash_exists) {
               existing_hashes.push_back(p.hash);
             }
@@ -167,7 +168,7 @@ void RenderTask::Render(const TimeRangeList& video_range,
       frame_queue.pop_front();
     }
 
-    if (!audio_queue.empty()) {
+    if (!IsCancelled() && !audio_queue.empty()) {
       audio_lookup_table.push_back({audio_queue.front(), backend_.RenderAudio(audio_queue.front())});
       audio_queue.pop_front();
     }
@@ -194,9 +195,9 @@ void RenderTask::Render(const TimeRangeList& video_range,
         // Place it in the cache
         std::list<rational> times_with_hash;
 
-        for (int k=0;k<hashes.size();k++) {
-          if (hashes.at(k) == j->hash) {
-            times_with_hash.push_back(times.at(k));
+        for (int hash_index=0;hash_index<hashes.size();hash_index++) {
+          if (hashes.at(hash_index) == j->hash) {
+            times_with_hash.push_back(times.at(hash_index));
           }
         }
 
diff --git a/app/widget/audiomonitor/audiomonitor.cpp b/app/widget/audiomonitor/audiomonitor.cpp
index 46a05a26e..86b53a8df 100644
--- a/app/widget/audiomonitor/audiomonitor.cpp
+++ b/app/widget/audiomonitor/audiomonitor.cpp
@@ -90,11 +90,11 @@ void AudioMonitor::Stop()
   }
 }
 
-void AudioMonitor::OutputPushed(const QByteArray &data)
+void AudioMonitor::OutputPushed(const QByteArray &d)
 {
   QVector<double> v(params_.channel_count(), 0);
 
-  BytesToSampleSummary(data, v);
+  BytesToSampleSummary(d, v);
 
   PushValue(v);
 
diff --git a/app/widget/audiomonitor/audiomonitor.h b/app/widget/audiomonitor/audiomonitor.h
index d2f55f287..2b290ff14 100644
--- a/app/widget/audiomonitor/audiomonitor.h
+++ b/app/widget/audiomonitor/audiomonitor.h
@@ -45,7 +45,7 @@ public slots:
 
   void Stop();
 
-  void OutputPushed(const QByteArray& data);
+  void OutputPushed(const QByteArray& d);
 
 protected:
   //virtual void paintEvent(QPaintEvent* event) override;
diff --git a/app/widget/menu/menu.cpp b/app/widget/menu/menu.cpp
index b744c3d32..5d1f7321c 100644
--- a/app/widget/menu/menu.cpp
+++ b/app/widget/menu/menu.cpp
@@ -50,13 +50,13 @@ Menu::Menu(const QString &s, QWidget *parent) :
   Init();
 }
 
-QAction *Menu::AddActionWithData(const QString &text, const QVariant &data, const QVariant &compare)
+QAction *Menu::AddActionWithData(const QString &text, const QVariant &d, const QVariant &compare)
 {
   QAction* a = addAction(text);
 
-  a->setData(data);
+  a->setData(d);
   a->setCheckable(true);
-  a->setChecked(data == compare);
+  a->setChecked(d == compare);
 
   return a;
 }
diff --git a/app/widget/menu/menu.h b/app/widget/menu/menu.h
index edafaf85d..777143efc 100644
--- a/app/widget/menu/menu.h
+++ b/app/widget/menu/menu.h
@@ -132,7 +132,7 @@ public:
   }
 
   QAction* AddActionWithData(const QString& text,
-                             const QVariant& data,
+                             const QVariant& d,
                              const QVariant& compare);
 
   QAction *InsertAlphabetically(const QString& s);
diff --git a/app/widget/timelinewidget/timelinewidget.cpp b/app/widget/timelinewidget/timelinewidget.cpp
index 908d7e3a2..b89ffe00d 100644
--- a/app/widget/timelinewidget/timelinewidget.cpp
+++ b/app/widget/timelinewidget/timelinewidget.cpp
@@ -1584,9 +1584,9 @@ bool TimelineWidget::SnapPoint(QList<rational> start_times, rational* movement,
 
   // Find all points at this movement
   QList<rational> snap_times;
-  foreach (const SnapData& data, potential_snaps) {
-    if (data.movement == *movement) {
-      snap_times.append(data.time);
+  foreach (const SnapData& d, potential_snaps) {
+    if (d.movement == *movement) {
+      snap_times.append(d.time);
     }
   }