diff --git a/src/ui.cpp b/src/ui.cpp
index 94eb173..c68d260 100644
--- a/src/ui.cpp
+++ b/src/ui.cpp
@@ -3449,7 +3449,7 @@ void math_canvas_draw(GtkDrawingArea*, cairo_t* cr, int width, int height, gpoin
       double px = 0.0;
       double py = 0.0;
       math_input_pos(n, k, px, py);
-      const bool armed = d->pending_out >= 0 && static_cast<int>(i) > d->pending_out;
+      const bool armed = d->pending_out >= 0 && static_cast<int>(i) != d->pending_out;
       cairo_set_source_rgb(cr, armed ? 1.0 : 0.45, armed ? 0.69 : 0.52, armed ? 0.13 : 0.62);
       cairo_rectangle(cr, px - kPort * 0.5, py - kPort * 0.5, kPort, kPort);
       cairo_fill(cr);