diff --git a/src/thermo.c b/src/thermo.c
index 71f7120..1e60872 100644
--- a/src/thermo.c
+++ b/src/thermo.c
@@ -83,5 +83,5 @@ void hexagram_thermo_draw_needle(hexagram_thermo *thermo,
     hexagram_gauge_draw_needle(&thermo->gauge,
                                cr,
                                0.9,
-                               temp / 260);
+                               (temp * (9.0/5.0) + 32.0) / 260);
 }