diff --git a/app/render/rendermanager.h b/app/render/rendermanager.h
index 325ba295a..39e01b01c 100644
--- a/app/render/rendermanager.h
+++ b/app/render/rendermanager.h
@@ -63,11 +63,11 @@ private:
 
 	bool cancelled_;
 
-	Renderer *context_;
+	Renderer *context_ = nullptr;
 
-	DecoderCache *decoder_cache_;
+	DecoderCache *decoder_cache_ = nullptr;
 
-	ShaderCache *shader_cache_;
+	ShaderCache *shader_cache_ = nullptr;
 };
 
 class RenderWorkerPool;
@@ -239,21 +239,21 @@ private:
 
 	static RenderManager *instance_;
 
-	Renderer *context_;
+	Renderer *context_ = nullptr;
 
 	Backend backend_;
 	Backend requested_backend_;
 
-	DecoderCache *decoder_cache_;
+	DecoderCache *decoder_cache_ = nullptr;
 
-	ShaderCache *shader_cache_;
+	ShaderCache *shader_cache_ = nullptr;
 
 	static constexpr auto kDecoderMaximumInactivityAggressive = 1000;
 	static constexpr auto kDecoderMaximumInactivity = 5000;
 
-	int aggressive_gc_;
+	int aggressive_gc_ = 0;
 
-	QTimer *decoder_clear_timer_;
+	QTimer *decoder_clear_timer_ = nullptr;
 
 	RenderThread *dry_run_thread_ = nullptr;
 	RenderThread *audio_thread_ = nullptr;
@@ -263,9 +263,9 @@ private:
 
 	std::list<RenderThread *> render_threads_;
 
-	PreviewAutoCacher *auto_cacher_;
+	PreviewAutoCacher *auto_cacher_ = nullptr;
 
-	RenderWorkerPool *worker_pool_;
+	RenderWorkerPool *worker_pool_ = nullptr;
 
 private slots:
 	void ClearOldDecoders();
diff --git a/app/task/project/loadotio/loadotio.cpp b/app/task/project/loadotio/loadotio.cpp
index 4b8eab907..1246b4439 100644
--- a/app/task/project/loadotio/loadotio.cpp
+++ b/app/task/project/loadotio/loadotio.cpp
@@ -94,6 +94,8 @@ bool LoadOTIOTask::Run()
 	} else {
 		// Unknown root, we don't know what to do with this
 		SetError(tr("Unknown OpenTimelineIO root element"));
+		delete project_;
+		project_ = nullptr;
 		return false;
 	}
 
diff --git a/app/widget/curvewidget/curveview.cpp b/app/widget/curvewidget/curveview.cpp
index 25e608bf6..cc044ae91 100644
--- a/app/widget/curvewidget/curveview.cpp
+++ b/app/widget/curvewidget/curveview.cpp
@@ -91,7 +91,7 @@ void CurveView::SelectKeyframesOfInput(const NodeKeyframeTrackReference &ref)
 {
 	DeselectAll();
 
-	foreach (KeyframeViewInputConnection *con, track_connections_) {
+	if (KeyframeViewInputConnection *con = track_connections_.value(ref)) {
 		foreach (NodeKeyframe *key, con->GetKeyframes()) {
 			SelectKeyframe(key);
 		}
diff --git a/app/widget/timeruler/seekablewidget.cpp b/app/widget/timeruler/seekablewidget.cpp
index cdeabc2f8..859d2824d 100644
--- a/app/widget/timeruler/seekablewidget.cpp
+++ b/app/widget/timeruler/seekablewidget.cpp
@@ -433,8 +433,9 @@ void SeekableWidget::SeekToScenePoint(qreal scene)
 		playhead_time += movement;
 	}
 
-	if (playhead_time != GetViewerNode()->GetPlayhead()) {
-		GetViewerNode()->SetPlayhead(playhead_time);
+	ViewerOutput *viewer = GetViewerNode();
+	if (viewer && playhead_time != viewer->GetPlayhead()) {
+		viewer->SetPlayhead(playhead_time);
 	}
 }
 
diff --git a/tests/gtest/render_misc_test.cpp b/tests/gtest/render_misc_test.cpp
index d16cff1db..aa9289199 100644
--- a/tests/gtest/render_misc_test.cpp
+++ b/tests/gtest/render_misc_test.cpp
@@ -712,3 +712,22 @@ TEST_F(RenderMiscAutoCacherTest, CacheProxyTaskCancelledClearsPendingJobs)
 
 	cacher.SetProject(nullptr);
 }
+
+// With an unknown/dummy graphics backend the RenderManager never creates the
+// GPU-side objects. Those pointers must be null (previously they were left
+// uninitialized, so callers such as ViewerWidget dereferenced garbage and
+// crashed).
+TEST(RenderManagerDummyBackend, GpuMembersAreNullRatherThanUninitialized)
+{
+	const QVariant previous =
+		olive::Config::Current()[QStringLiteral("GraphicsBackend")];
+	olive::Config::Current()[QStringLiteral("GraphicsBackend")] =
+		QStringLiteral("dummy");
+
+	olive::RenderManager::CreateInstance();
+
+	EXPECT_EQ(olive::RenderManager::instance()->GetCacher(), nullptr);
+
+	olive::RenderManager::DestroyInstance();
+	olive::Config::Current()[QStringLiteral("GraphicsBackend")] = previous;
+}
diff --git a/tests/gtest/widget_curve_keyframe_test.cpp b/tests/gtest/widget_curve_keyframe_test.cpp
index 27b575cc7..031511e55 100644
--- a/tests/gtest/widget_curve_keyframe_test.cpp
+++ b/tests/gtest/widget_curve_keyframe_test.cpp
@@ -344,6 +344,34 @@ TEST_F(CurveViewTest, SetKeyframeTrackColorAppliesToBrush)
 	EXPECT_EQ(connection->GetBrush().color(), QColor(Qt::blue));
 }
 
+TEST_F(CurveViewTest, SelectKeyframesOfInputSelectsOnlyRequestedTrack)
+{
+	class SelectionProbeCurveView : public CurveView {
+	public:
+		using KeyframeView::IsKeyframeSelected;
+	};
+
+	SelectionProbeCurveView view;
+	view.ConnectInput(ColorTrackRef(0));
+	view.ConnectInput(ColorTrackRef(1));
+
+	NodeKeyframe *key0 =
+		InsertKeyframe(solid_, SolidGenerator::kColorInput, rational(0), 0.5, 0);
+	NodeKeyframe *key1 =
+		InsertKeyframe(solid_, SolidGenerator::kColorInput, rational(1), 0.6, 1);
+
+	// Previously the reference was ignored and keyframes of every connected
+	// track got selected.
+	view.SelectKeyframesOfInput(ColorTrackRef(0));
+	EXPECT_TRUE(view.IsKeyframeSelected(key0));
+	EXPECT_FALSE(view.IsKeyframeSelected(key1));
+
+	// Selecting the other track replaces the selection (DeselectAll first)
+	view.SelectKeyframesOfInput(ColorTrackRef(1));
+	EXPECT_FALSE(view.IsKeyframeSelected(key0));
+	EXPECT_TRUE(view.IsKeyframeSelected(key1));
+}
+
 TEST(CurveWidget, VerticalScaleRoundTripsThroughView)
 {
 	ColorManager::SetUpDefaultConfig();
diff --git a/tests/gtest/widget_timeruler_playback_test.cpp b/tests/gtest/widget_timeruler_playback_test.cpp
index 1c86594e9..b32010442 100644
--- a/tests/gtest/widget_timeruler_playback_test.cpp
+++ b/tests/gtest/widget_timeruler_playback_test.cpp
@@ -100,6 +100,20 @@ TEST(TimeRuler, SeekToScenePointWithoutTimebaseIsNoOp)
 	SUCCEED();
 }
 
+TEST(TimeRuler, SeekToScenePointWithoutViewerIsNoOp)
+{
+	EnsureAppSingletons();
+
+	// Timebase set but no viewer connected: previously dereferenced a null
+	// GetViewerNode() and crashed.
+	TimeRuler ruler;
+	ruler.SetTimebase(rational(1, 30));
+	ruler.SetScale(100.0);
+
+	ruler.SeekToScenePoint(150.0);
+	SUCCEED();
+}
+
 class PlaybackControlsTest : public ::testing::Test {
 protected:
 	void SetUp() override