diff --git a/Outputs/OpenGL/ScanTarget.cpp b/Outputs/OpenGL/ScanTarget.cpp
index 4990c3e64..3a30d9811 100644
--- a/Outputs/OpenGL/ScanTarget.cpp
+++ b/Outputs/OpenGL/ScanTarget.cpp
@@ -174,8 +174,12 @@ void ScanTarget::set_modals(Modals modals) {
 }
 
 void Outputs::Display::OpenGL::ScanTarget::set_uniforms(ShaderType type, Shader &target) {
+	// Slightly over-amping rowHeight here is a cheap way to make sure that lines
+	// converge even allowing for the fact that they may not be spaced by exactly
+	// the expected distance. Cf. the stencil-powered logic for making sure all
+	// pixels are painted only exactly once per field.
+	target.set_uniform("rowHeight", GLfloat(1.05f / modals_.expected_vertical_lines));
 	target.set_uniform("scale", GLfloat(modals_.output_scale.x), GLfloat(modals_.output_scale.y));
-	target.set_uniform("rowHeight", GLfloat(1.0f / modals_.expected_vertical_lines));
 	target.set_uniform("processingWidth", GLfloat(processing_width_) / 2048.0f);
 }