Index: src/thermal.c
===================================================================
--- src/thermal.c	(revision 18962)
+++ src/thermal.c	(revision 18963)
@@ -137,6 +137,11 @@
 		atmp.Delta = ea-sa;
 	}
 	else {
+		if (ea < sa) {
+			double tmp = ea;
+			ea = sa;
+			sa = tmp;
+		}
 		atmp.StartAngle = ea;
 		atmp.Delta = 360-ea+sa;
 	}