diff --git a/quickdialog/QAppearance.h b/quickdialog/QAppearance.h
index 50e49dc7..a9461c32 100644
--- a/quickdialog/QAppearance.h
+++ b/quickdialog/QAppearance.h
@@ -33,8 +33,8 @@
 @property(nonatomic, strong) UIColor *sectionTitleShadowColor;
 @property(nonatomic) BOOL toolbarTranslucent;
 @property(nonatomic) CGFloat cellBorderWidth;
-@property(nonatomic) NSNumber * defaultHeightForHeader;
-@property(nonatomic) NSNumber * defaultHeightForFooter;
+@property(nonatomic, strong) NSNumber * defaultHeightForHeader;
+@property(nonatomic, strong) NSNumber * defaultHeightForFooter;
 
 @property(nonatomic) UIBarStyle toolbarStyle;