diff --git a/ASValueTrackingSlider/ASValuePopUpView.m b/ASValueTrackingSlider/ASValuePopUpView.m
index f8617cc..0790580 100644
--- a/ASValueTrackingSlider/ASValuePopUpView.m
+++ b/ASValueTrackingSlider/ASValuePopUpView.m
@@ -136,7 +136,7 @@ - (void)setFont:(UIFont *)font
                               value:font
                               range:NSMakeRange(0, [_attributedString length])];
     
-    _textLayer.font = (__bridge CFTypeRef)(font.fontName);
+    _textLayer.font = (__bridge CFTypeRef _Nullable)(font);
     _textLayer.fontSize = font.pointSize;
 }