diff --git a/profile.c b/profile.c
index 2dce8003b..4b04d68ce 100644
--- a/profile.c
+++ b/profile.c
@@ -883,7 +883,7 @@ static int setup_temperature_limits(struct graphics_context *gc, struct plot_inf
 		gc->bottomy = mintemp - delta / 3;
 
 	pi->endtempcoord = SCALEY(gc, pi->mintemp);
-	return maxtemp >= mintemp;
+	return maxtemp && maxtemp >= mintemp;
 }
 
 static void plot_single_temp_text(struct graphics_context *gc, int sec, int mkelvin)