diff --git a/PortabilityLayer/EllipsePlotter.cpp b/PortabilityLayer/EllipsePlotter.cpp
index d6c9e4e..c4c7c52 100644
--- a/PortabilityLayer/EllipsePlotter.cpp
+++ b/PortabilityLayer/EllipsePlotter.cpp
@@ -73,9 +73,9 @@ namespace PortabilityLayer
 				const int32_t xStepCost = -m_xChangeCostDynamicFactor + m_xChangeCostStaticFactor;
 				const int32_t yStepCost = m_yChangeCostDynamicFactor + m_yChangeCostStaticFactor;
 
-				const int32_t diagonalCostDelta = xStepCost + yStepCost;
+				const int32_t tangentCalc = (-m_xChangeCostDynamicFactor) + m_yChangeCostDynamicFactor;
 
-				if (diagonalCostDelta < 0)
+				if (tangentCalc < 0)
 				{
 					// Diagonal movement will move closer to the edge (first octant)
 					IncrementY();
@@ -115,9 +115,9 @@ namespace PortabilityLayer
 				const int32_t xStepCost = -m_xChangeCostDynamicFactor + m_xChangeCostStaticFactor;
 				const int32_t yStepCost = -m_yChangeCostDynamicFactor + m_yChangeCostStaticFactor;
 
-				const int32_t diagonalCostDelta = xStepCost + yStepCost;
+				const int32_t tangentCalc = (-m_xChangeCostDynamicFactor) + (-m_yChangeCostDynamicFactor);
 
-				if (diagonalCostDelta < 0)
+				if (tangentCalc < 0)
 				{
 					// Diagonal movement will move closer to the edge (first octant)
 					DecrementX();
@@ -157,9 +157,9 @@ namespace PortabilityLayer
 				const int32_t xStepCost = m_xChangeCostDynamicFactor + m_xChangeCostStaticFactor;
 				const int32_t yStepCost = -m_yChangeCostDynamicFactor + m_yChangeCostStaticFactor;
 
-				const int32_t diagonalCostDelta = xStepCost + yStepCost;
+				const int32_t tangentCalc = (m_xChangeCostDynamicFactor) + (-m_yChangeCostDynamicFactor);
 
-				if (diagonalCostDelta < 0)
+				if (tangentCalc < 0)
 				{
 					// Diagonal movement will move closer to the edge (first octant)
 					DecrementY();
@@ -199,9 +199,9 @@ namespace PortabilityLayer
 				const int32_t xStepCost = m_xChangeCostDynamicFactor + m_xChangeCostStaticFactor;
 				const int32_t yStepCost = m_yChangeCostDynamicFactor + m_yChangeCostStaticFactor;
 
-				const int32_t diagonalCostDelta = xStepCost + yStepCost;
+				const int32_t tangentCalc = m_xChangeCostDynamicFactor + m_yChangeCostDynamicFactor;
 
-				if (diagonalCostDelta < 0)
+				if (tangentCalc < 0)
 				{
 					// Diagonal movement will move closer to the edge (first octant)
 					IncrementX();
diff --git a/PortabilityLayer/PLQDraw.cpp b/PortabilityLayer/PLQDraw.cpp
index 88e8c1c..4f93f5d 100644
--- a/PortabilityLayer/PLQDraw.cpp
+++ b/PortabilityLayer/PLQDraw.cpp
@@ -1014,9 +1014,15 @@ void DrawSurface::SetSystemFont(int size, int variationFlags)
 
 void DrawSurface::FillEllipse(const Rect &rect)
 {
-	if (!rect.IsValid())
+	if (!rect.IsValid() || rect.Width() < 1 || rect.Height() < 1)
 		return;
 
+	if (rect.Width() <= 2 || rect.Height() <= 2)
+	{
+		FillRect(rect);
+		return;
+	}
+
 	PortabilityLayer::ScanlineMask *mask = PortabilityLayer::ScanlineMaskConverter::CompileEllipse(PortabilityLayer::Rect2i(rect.top, rect.left, rect.bottom, rect.right));
 	if (mask)
 	{