Update src/npctalk.cpp

Author: Maleclypse

src/npctalk.cpp

@@ -3511,18 +3511,22 @@ talk_effect_fun_t::func f_add_trait( const JsonObject &jo, std::string_view memb
 
         const auto &new_types = trait->types;
 
-        for( const std::string &t : existing_types ) {
-            bool match = false;
-            if constexpr( std::is_same_v<decltype( new_types ), const std::set<std::string> & > ) {
-                match = new_types.count( t ) > 0;
-            } else {
-                match = new_types.count( t ) > 0;
-            }
-            if( match ) {
-                guy->unset_mutation( existing );
-                break;
+        for( const trait_id &existing : guy->get_mutations() ) {
+            if( existing == trait ) {
+                continue;
             }
-        }
+            const auto &existing_types = existing->types;
+            for( const std::string &t : existing_types ) {
+                bool match = false;
+                if constexpr( std::is_same<decltype( new_types ), const std::set<std::string> &>::value ) {
+                    match = new_types.count( t ) > 0;
+                } else {
+                    match = std::find( new_types.begin(), new_types.end(), t ) != new_types.end();
+                }
+                if( match ) {
+                    guy->unset_mutation( existing );
+                    break;
+                }
 
         d.actor( is_npc )->set_mutation( trait, variant );
     };