diff --git a/src/xrt/drivers/north_star/distortion/deformation_northstar.cpp b/src/xrt/drivers/north_star/distortion/deformation_northstar.cpp
index 87d336e3d..0e918c623 100644
--- a/src/xrt/drivers/north_star/distortion/deformation_northstar.cpp
+++ b/src/xrt/drivers/north_star/distortion/deformation_northstar.cpp
@@ -189,14 +189,14 @@ OpticalSystem::RenderUVToDisplayUV(const Vector3 &inputUV)
 
 Vector2
 OpticalSystem::SolveDisplayUVToRenderUV(const Vector2 &inputUV,
-                                        Vector2 initailGuess,
+                                        Vector2 const &initialGuess,
                                         int iterations)
 {
 
-	float epsilon = 0.0001f;
+	static const float epsilon = 0.0001f;
 	Vector2 curCameraUV;
-	curCameraUV.x = initailGuess.x;
-	curCameraUV.y = initailGuess.y;
+	curCameraUV.x = initialGuess.x;
+	curCameraUV.y = initialGuess.y;
 	Vector2 curDisplayUV;
 
 	for (int i = 0; i < iterations; i++) {
diff --git a/src/xrt/drivers/north_star/distortion/deformation_northstar.h b/src/xrt/drivers/north_star/distortion/deformation_northstar.h
index a6b0070d0..77db03bcd 100644
--- a/src/xrt/drivers/north_star/distortion/deformation_northstar.h
+++ b/src/xrt/drivers/north_star/distortion/deformation_northstar.h
@@ -33,7 +33,7 @@ public:
 
 	Vector2
 	SolveDisplayUVToRenderUV(const Vector2 &inputUV,
-	                         Vector2 initailGuess,
+	                         Vector2 const &initialGuess,
 	                         int iterations);
 
 	Vector2