diff --git a/src/mutation.cpp b/src/mutation.cpp
index bf019939a2f4e..a6e24ede0015a 100644
--- a/src/mutation.cpp
+++ b/src/mutation.cpp
@@ -285,7 +285,7 @@ void Character::mutation_reflex_trigger( const trait_id &mut )
     }
 }
 
-bool reflex_activation_data::is_trigger_true( const Character &guy ) const
+bool reflex_activation_data::is_trigger_true( Character &guy ) const
 {
     dialogue d( get_talker_for( guy ), nullptr );
     return trigger( d );
diff --git a/src/mutation.h b/src/mutation.h
index 1c7157227b879..a70a681fff222 100644
--- a/src/mutation.h
+++ b/src/mutation.h
@@ -100,7 +100,7 @@ struct reflex_activation_data {
     std::pair<translation, game_message_type> msg_on;
     std::pair<translation, game_message_type> msg_off;
 
-    bool is_trigger_true( const Character &guy ) const;
+    bool is_trigger_true( Character &guy ) const;
 
     bool was_loaded = false;
     void load( const JsonObject &jsobj );