From 1e74387d3d9291958ce1611e2225a9cd03725050 Mon Sep 17 00:00:00 2001
From: Celtic Minstrel <celtic.minstrel.ca@some.place>
Date: Tue, 18 Aug 2015 11:16:38 -0400
Subject: [PATCH] Handle case of default (-1) in [effect]apply_to=vision

---
 src/unit.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/unit.cpp b/src/unit.cpp
index 1051a811e39..cb17fa669be 100644
--- a/src/unit.cpp
+++ b/src/unit.cpp
@@ -1791,7 +1791,8 @@ void unit::add_modification(const std::string& mod_type, const config& mod, bool
 								t_string(N_("vision"), "wesnoth");
 						}
 
-						vision_ = utils::apply_modifier(vision_, increase, 1);
+						const int current_vision = vision_ < 0 ? max_movement_ : vision_;
+						vision_ = utils::apply_modifier(current_vision, increase, 1);
 					}
 
 					vision_ = effect["set"].to_int(vision_);