diff --git a/src/engine/controls/ratecontrol.cpp b/src/engine/controls/ratecontrol.cpp
index 89daa21a3cf7..9b496f485df7 100644
--- a/src/engine/controls/ratecontrol.cpp
+++ b/src/engine/controls/ratecontrol.cpp
@@ -189,9 +189,6 @@ RateControl::RateControl(const QString& group, UserSettingsPointer pConfig)
             &RateControl::slotControlRatePermUpSmall,
             Qt::DirectConnection);
 
-
-
-
     // Scratch enable toggle
     m_pScratch2Enable->set(0);
 
diff --git a/src/engine/positionscratchcontroller.cpp b/src/engine/positionscratchcontroller.cpp
index 94812b260e7e..16f7a9eb98ed 100644
--- a/src/engine/positionscratchcontroller.cpp
+++ b/src/engine/positionscratchcontroller.cpp
@@ -8,49 +8,62 @@
 #include "util/math.h"
 #include "util/time.h"
 
-VelocityController::VelocityController()
-        : m_last_error(0.0),
-          m_p(0.0),
-          m_d(0.0) {
-}
+class VelocityController {
+  public:
+    VelocityController()
+            : m_last_error(0.0),
+              m_p(0.0),
+              m_d(0.0) {
+    }
+    void setPD(double p, double d) {
+        m_p = p;
+        m_d = d;
+    }
 
-void VelocityController::setPD(double p, double d) {
-    m_p = p;
-    m_d = d;
-}
+    void reset(double last_error) {
+        m_last_error = last_error;
+    }
 
-void VelocityController::reset(double last_error) {
-    m_last_error = last_error;
-}
+    double observation(double error) {
+        // Main PD calculation
+        m_last_error = m_p * error + m_d * (error - m_last_error);
+        return m_last_error;
+    }
 
-double VelocityController::observation(double error) {
-    // Main PD calculation
-    m_last_error = m_p * error + m_d * (error - m_last_error);
-    return m_last_error;
-}
+  private:
+    double m_last_error;
+    double m_p, m_d;
+};
 
-RateIIFilter::RateIIFilter()
-        : m_factor(1.0),
-          m_last_rate(0.0) {
-}
+class RateIIFilter {
+  public:
+    RateIIFilter()
+            : m_factor(1.0),
+              m_last_rate(0.0) {
+    }
 
-void RateIIFilter::setFactor(double factor) {
-    m_factor = factor;
-}
+    void setFactor(double factor) {
+        m_factor = factor;
+    }
 
-void RateIIFilter::reset(double last_rate) {
-    m_last_rate = last_rate;
-}
+    void reset(double last_rate) {
+        m_last_rate = last_rate;
+    }
 
-double RateIIFilter::filter(double rate) {
-    if (fabs(rate) - fabs(m_last_rate) > -0.1) {
-        m_last_rate = m_last_rate * (1 - m_factor) + rate * m_factor;
-    } else {
-        // do not filter strong decelerations to avoid overshooting
-        m_last_rate = rate;
+    double filter(double rate) {
+        if (fabs(rate) - fabs(m_last_rate) > -0.1) {
+            m_last_rate = m_last_rate * (1 - m_factor) + rate * m_factor;
+        } else {
+            // do not filter strong decelerations to avoid overshooting
+            m_last_rate = rate;
+        }
+        return m_last_rate;
     }
-    return m_last_rate;
-}
+
+  private:
+    double m_factor;
+    double m_last_rate;
+};
 
 namespace {
 
@@ -69,6 +82,14 @@ constexpr double kTimeToStop = 1.0;
 
 PositionScratchController::PositionScratchController(const QString& group)
         : m_group(group),
+          m_pScratchEnable(std::make_unique<ControlObject>(
+                  ConfigKey(group, QStringLiteral("scratch_position_enable")))),
+          m_pScratchPos(std::make_unique<ControlObject>(
+                  ConfigKey(group, QStringLiteral("scratch_position")))),
+          m_pMainSampleRate(std::make_unique<ControlProxy>(
+                  ConfigKey(QStringLiteral("[App]"), QStringLiteral("samplerate")))),
+          m_pVelocityController(std::make_unique<VelocityController>()),
+          m_pRateIIFilter(std::make_unique<RateIIFilter>()),
           m_isScratching(false),
           m_inertiaEnabled(false),
           m_prevSamplePos(0),
@@ -84,19 +105,11 @@ PositionScratchController::PositionScratchController(const QString& group)
           m_p(1),
           m_d(1),
           m_f(0.4) {
-    m_pScratchEnable = std::make_unique<ControlObject>(
-            ConfigKey(group, QStringLiteral("scratch_position_enable")));
-
-    m_pScratchPos = std::make_unique<ControlObject>(
-            ConfigKey(group, QStringLiteral("scratch_position")));
-
-    m_pMainSampleRate = std::make_unique<ControlProxy>(
-            ConfigKey(QStringLiteral("[App]"), QStringLiteral("samplerate")));
     m_pMainSampleRate->connectValueChanged(this,
             &PositionScratchController::slotSampleRateChanged);
+}
 
-    m_pVelocityController = std::make_unique<VelocityController>();
-    m_pRateIIFilter = std::make_unique<RateIIFilter>();
+PositionScratchController::~PositionScratchController() {
 }
 
 void PositionScratchController::slotSampleRateChanged(double sampleRate) {
diff --git a/src/engine/positionscratchcontroller.h b/src/engine/positionscratchcontroller.h
index 5eb5a4b7f89f..b91b98ce2cb6 100644
--- a/src/engine/positionscratchcontroller.h
+++ b/src/engine/positionscratchcontroller.h
@@ -7,37 +7,16 @@
 
 class ControlObject;
 class ControlProxy;
-
-class VelocityController {
-  public:
-    VelocityController();
-
-    void setPD(double p, double d);
-    void reset(double last_error);
-    double observation(double error);
-
-  private:
-    double m_last_error;
-    double m_p, m_d;
-};
-
-class RateIIFilter {
-  public:
-    RateIIFilter();
-
-    void setFactor(double factor);
-    void reset(double last_rate);
-    double filter(double rate);
-
-  private:
-    double m_factor;
-    double m_last_rate;
-};
+class VelocityController;
+class RateIIFilter;
 
 class PositionScratchController : public QObject {
     Q_OBJECT
   public:
     PositionScratchController(const QString& group);
+    // required for the forward-declarations of uniquq_pointers of
+    // VelocityController and RateIIFilter
+    ~PositionScratchController();
 
     void process(double currentSample,
             double releaseRate,