1 files changed, 1 insertions, 1 deletions
diff --git a/tikzit/src/common/EdgeStyle.h b/tikzit/src/common/EdgeStyle.h
index 66144f4..248d8f4 100644
--- a/tikzit/src/common/EdgeStyle.h
+++ b/tikzit/src/common/EdgeStyle.h
@@ -36,7 +36,7 @@ typedef enum {
     ED_Tick = 2
 } EdgeDectorationStyle;
 
-@interface EdgeStyle : PropertyHolder {
+@interface EdgeStyle : PropertyHolder <NSCopying> {
     ArrowHeadStyle headStyle, tailStyle;
     EdgeDectorationStyle decorationStyle;
     float thickness;