[style] Fix float conversion warning
diff --git a/src/hb-style.cc b/src/hb-style.cc
index 35871de..9345c24 100644
--- a/src/hb-style.cc
+++ b/src/hb-style.cc
@@ -49,13 +49,13 @@
 static inline float
 _hb_angle_to_ratio (float a)
 {
-  return tanf (a * (M_PI / 180.f));
+  return tanf (a * float (M_PI / 180.));
 }
 #if 0
 static inline float
 _hb_ratio_to_angle (float r)
 {
-  return atanf (r) * (180.f / M_PI);
+  return atanf (r) * float (180. / M_PI);
 }
 #endif