diff --git a/src/mapper/mapper.cc b/src/mapper/mapper.cc
index a3885e9..da5072b 100644
--- a/src/mapper/mapper.cc
+++ b/src/mapper/mapper.cc
@@ -1,15 +1,45 @@
 #include "mapper/mapper.h"
 
+#include "game_mouse.h"
 #include "object.h"
 #include "proto.h"
 
 namespace fallout {
 
+static int mapper_mark_exit_grid();
 static void mapper_mark_all_exit_grids();
 
 // 0x559748
 MapTransition mapInfo = { -1, -1, 0, 0 };
 
+// 0x48C678
+int mapper_mark_exit_grid()
+{
+    int y;
+    int x;
+    int tile;
+    Object* obj;
+
+    for (y = -2000; y != 2000; y += 200) {
+        for (x = -10; x < 10; x++) {
+            tile = gGameMouseBouncingCursor->tile + y + x;
+
+            obj = objectFindFirstAtElevation(gElevation);
+            while (obj != NULL) {
+                if (isExitGridPid(obj->pid)) {
+                    obj->data.misc.map = mapInfo.map;
+                    obj->data.misc.tile = mapInfo.tile;
+                    obj->data.misc.elevation = mapInfo.elevation;
+                    obj->data.misc.rotation = mapInfo.rotation;
+                }
+                obj = objectFindNextAtElevation();
+            }
+        }
+    }
+
+    return 0;
+}
+
 // 0x48C704
 void mapper_mark_all_exit_grids()
 {