diff --git a/src/object.cc b/src/object.cc
index b4f18f0..4df1512 100644
--- a/src/object.cc
+++ b/src/object.cc
@@ -1481,11 +1481,11 @@ int objectSetLocation(Object* obj, int tile, int elevation, Rect* rect)
 
             if (isEmpty != _obj_last_is_empty || (((currentSquare >> 16) & 0xF000) >> 12) != (((previousSquare >> 16) & 0xF000) >> 12)) {
                 if (!_obj_last_is_empty) {
-                    _tile_fill_roof(_obj_last_roof_x, _obj_last_roof_y, elevation, 1);
+                    tile_fill_roof(_obj_last_roof_x, _obj_last_roof_y, elevation, true);
                 }
 
                 if (!isEmpty) {
-                    _tile_fill_roof(roofX, roofY, elevation, 0);
+                    tile_fill_roof(roofX, roofY, elevation, false);
                 }
 
                 if (rect != NULL) {
@@ -1528,7 +1528,7 @@ int _obj_reset_roof()
 {
     int fid = buildFid(OBJ_TYPE_TILE, (_square[gDude->elevation]->field_0[_obj_last_roof_x + 100 * _obj_last_roof_y] >> 16) & 0xFFF, 0, 0, 0);
     if (fid != buildFid(OBJ_TYPE_TILE, 1, 0, 0, 0)) {
-        _tile_fill_roof(_obj_last_roof_x, _obj_last_roof_y, gDude->elevation, 1);
+        tile_fill_roof(_obj_last_roof_x, _obj_last_roof_y, gDude->elevation, 1);
     }
     return 0;
 }
diff --git a/src/tile.cc b/src/tile.cc
index e3165a6..4d247f8 100644
--- a/src/tile.cc
+++ b/src/tile.cc
@@ -1266,12 +1266,12 @@ static void roof_fill_on(int x, int y, int elevation)
 }
 
 // 0x4B23D4
-void _tile_fill_roof(int a1, int a2, int elevation, int a4)
+void tile_fill_roof(int x, int y, int elevation, bool on)
 {
-    if (a4) {
-        roof_fill_on(a1, a2, elevation);
+    if (on) {
+        roof_fill_on(x, y, elevation);
     } else {
-        roof_fill_off(a1, a2, elevation);
+        roof_fill_off(x, y, elevation);
     }
 }
 
diff --git a/src/tile.h b/src/tile.h
index 54f20a0..398e777 100644
--- a/src/tile.h
+++ b/src/tile.h
@@ -48,7 +48,7 @@ int squareTileFromScreenXY(int screenX, int screenY, int elevation);
 void squareTileScreenToCoord(int screenX, int screenY, int elevation, int* coordX, int* coordY);
 void squareTileScreenToCoordRoof(int screenX, int screenY, int elevation, int* coordX, int* coordY);
 void tileRenderRoofsInRect(Rect* rect, int elevation);
-void _tile_fill_roof(int x, int y, int elevation, int a4);
+void tile_fill_roof(int x, int y, int elevation, bool on);
 void tileRenderFloorsInRect(Rect* rect, int elevation);
 bool _square_roof_intersect(int x, int y, int elevation);
 void _grid_render(Rect* rect, int elevation);