diff --git a/src/app/Knob.cpp b/src/app/Knob.cpp
index 97aad162..1be1129b 100644
--- a/src/app/Knob.cpp
+++ b/src/app/Knob.cpp
@@ -10,7 +10,6 @@ namespace rack {
 
 static const float KNOB_SENSITIVITY = 0.0015f;
 
-
 Knob::Knob() {
 	// smooth = true;
 	smooth = false;  // xxx
@@ -18,30 +17,54 @@ Knob::Knob() {
 
 void Knob::onDragStart(EventDragStart &e) {
 	windowCursorLock();
-	dragValue = value;
+   // printf("xxx Knob::onDragStart: value=%f\n", value);
+   dragValue = value;
 	randomizable = false;
 }
 
 void Knob::onDragMove(EventDragMove &e) {
 	float range;
+   // printf("xxx Knob::onDragMove: minValue=%f maxValue=%f\n", minValue, maxValue);
+
 	if (isfinite(minValue) && isfinite(maxValue)) {
+      // Regular knob
 		range = maxValue - minValue;
+
+      float delta = KNOB_SENSITIVITY * -e.mouseRel.y * speed * range;
+      // Drag slower if Mod is held
+      if (windowIsModPressed())
+         delta /= 16.f;
+      dragValue += delta;
+      dragValue = clamp2(dragValue, minValue, maxValue);
+
+      if (snap)
+         setValue(roundf(dragValue));
+      else
+         setValue(dragValue);
+
+      // printf("xxx Knob::onDragMove: dragValue=%f delta=%f value=%f snap=%d\n", dragValue, delta, value, snap);
 	}
 	else {
 		// Continuous encoders scale as if their limits are +/-1
 		range = 1.f - (-1.f);
+      // printf("xxx Knob::onDragMove: range=inf (+-1)\n");
+
+      float delta = KNOB_SENSITIVITY * -e.mouseRel.y * speed * range;
+      // Drag slower if Mod is held
+      if (windowIsModPressed())
+         delta /= 16.f;
+
+      dragValue += delta;
+
+      this->value = dragValue;
+
+      // printf("xxx Knob::onDragMove: inf dragValue=%f delta=%f value=%f\n", dragValue, delta, value);
+
+      EventChange e;
+      onChange(e);
+
+      // printf("xxx Knob::onDragMove: LEAVE inf dragValue=%f delta=%f value=%f\n", dragValue, delta, value);
 	}
-	float delta = KNOB_SENSITIVITY * -e.mouseRel.y * speed * range;
-
-	// Drag slower if Mod is held
-	if (windowIsModPressed())
-		delta /= 16.f;
-	dragValue += delta;
-	dragValue = clamp2(dragValue, minValue, maxValue);
-	if (snap)
-		setValue(roundf(dragValue));
-	else
-		setValue(dragValue);
 }
 
 void Knob::onDragEnd(EventDragEnd &e) {
diff --git a/src/app/ParamWidget.cpp b/src/app/ParamWidget.cpp
index b16bda34..2ed16b60 100644
--- a/src/app/ParamWidget.cpp
+++ b/src/app/ParamWidget.cpp
@@ -47,7 +47,7 @@ void ParamWidget::onChange(EventChange &e) {
 	if (!module)
 		return;
 
-   // printf("xxx ParamWidget::onChange: paramId=%d value=%f\n", paramId, value);
+   // printf("xxx ParamWidget::onChange: paramId=%d value=%f this=%p smooth=%d\n", paramId, value, this, smooth);
 
 	if (smooth)
 		engineSetParamSmooth(module, paramId, value);
diff --git a/src/engine.cpp b/src/engine.cpp
index 9e6e5ef1..d30672be 100644
--- a/src/engine.cpp
+++ b/src/engine.cpp
@@ -297,15 +297,18 @@ void engineSetParam(Module *module, int paramId, float value) {
             ParamWidget *paramWidget = moduleWidget->findParamWidgetByParamId(paramId);
             if(NULL != paramWidget)
             {
-               // Normalize parameter
-               float paramRange = (paramWidget->maxValue - paramWidget->minValue);
-               if(paramRange > 0.0f)
+               if(isfinite(paramWidget->minValue) && isfinite(paramWidget->maxValue))
                {
-                  float normValue = (value - paramWidget->minValue) / paramRange;
-                  // printf("xxx paramId=%d normValue=%f\n", paramId, normValue);
+                  // Normalize parameter
+                  float paramRange = (paramWidget->maxValue - paramWidget->minValue);
+                  if(paramRange > 0.0f)
+                  {
+                     float normValue = (value - paramWidget->minValue) / paramRange;
+                     // printf("xxx paramId=%d normValue=%f\n", paramId, normValue);
 
-                  // Call host audioMasterAutomate
-                  vst2_handle_ui_param(uniqueParamId, normValue);
+                     // Call host audioMasterAutomate
+                     vst2_handle_ui_param(uniqueParamId, normValue);
+                  }
                }
             }
          }
@@ -357,16 +360,19 @@ void vst2_handle_queued_params(void) {
                if(NULL != paramWidget)
                {
                   // Normalize parameter
-                  float paramRange = (paramWidget->maxValue - paramWidget->minValue);
-                  if(paramRange > 0.0f)
+                  if(isfinite(paramWidget->minValue) && isfinite(paramWidget->maxValue))
                   {
-                     // float value = qp.norm_value - 0.5f;
-                     // value *= 2.0f;
-                     float value = (qp.norm_value * paramRange) + paramWidget->minValue;
-                     engineSetParam(module, paramId, value, false/*bVSTAutomate*/);
-
-                     // Update UI widget
-                     paramWidget->setValue(value);
+                     float paramRange = (paramWidget->maxValue - paramWidget->minValue);
+                     if(paramRange > 0.0f)
+                     {
+                        // float value = qp.norm_value - 0.5f;
+                        // value *= 2.0f;
+                        float value = (qp.norm_value * paramRange) + paramWidget->minValue;
+                        engineSetParam(module, paramId, value, false/*bVSTAutomate*/);
+
+                        // Update UI widget
+                        paramWidget->setValue(value);
+                     }
                   }
                }
             }
diff --git a/src/widgets/QuantityWidget.cpp b/src/widgets/QuantityWidget.cpp
index 5746616b..62fce5a0 100644
--- a/src/widgets/QuantityWidget.cpp
+++ b/src/widgets/QuantityWidget.cpp
@@ -9,9 +9,21 @@ QuantityWidget::QuantityWidget() {
 }
 
 void QuantityWidget::setValue(float value) {
-	this->value = clamp(value, fminf(minValue, maxValue), fmaxf(minValue, maxValue));
-	EventChange e;
-	onChange(e);
+   // printf("xxx QuantityWidget::setValue: value=%f\n", value);
+   if(isfinite(minValue) && isfinite(maxValue))
+   {
+      this->value = clamp(value, fminf(minValue, maxValue), fmaxf(minValue, maxValue));
+      EventChange e;
+      onChange(e);
+   }
+   else
+   {
+      // Rotary knob
+      this->value = value;
+      EventChange e;
+      onChange(e);
+   }
+   // printf("xxx QuantityWidget::setValue: LEAVE value=%f\n", value);
 }
 
 void QuantityWidget::setLimits(float minValue, float maxValue) {