diff --git a/lib/mapObjects/CGPandoraBox.cpp b/lib/mapObjects/CGPandoraBox.cpp
index 1ddf2d997..4fa3e50df 100644
--- a/lib/mapObjects/CGPandoraBox.cpp
+++ b/lib/mapObjects/CGPandoraBox.cpp
@@ -212,7 +212,7 @@ void CGPandoraBox::serializeJsonOptions(JsonSerializeFormat & handler)
 			for(int idx = 0; idx < reward.primary.size(); idx ++)
 			{
 				handler.serializeInt(NPrimarySkill::names[idx], reward.primary[idx], 0);
-				updateReward |= reward.primary[idx];
+				updateReward |= bool(reward.primary[idx]);
 			}
 			addReward(updateReward);
 		}