diff --git a/src/raster/dirty.cpp b/src/raster/dirty.cpp
index 25ab538e2..4c69104f8 100644
--- a/src/raster/dirty.cpp
+++ b/src/raster/dirty.cpp
@@ -130,7 +130,7 @@ static void swap_hline32(void* image, void* data, int x1, int x2);
 static void swap_hline16(void* image, void* data, int x1, int x2);
 static void swap_hline8(void* image, void* data, int x1, int x2);
 
-Dirty* dirty_new(Image* image, int x1, int y1, int x2, int y2, int tiled)
+Dirty* dirty_new(Image* image, int x1, int y1, int x2, int y2, bool tiled)
 {
   Dirty* dirty;
 
diff --git a/src/raster/dirty.h b/src/raster/dirty.h
index c4903b834..75fec054f 100644
--- a/src/raster/dirty.h
+++ b/src/raster/dirty.h
@@ -48,13 +48,13 @@ struct Dirty
   Image* image;
   int x1, y1;
   int x2, y2;
-  int tiled;
+  bool tiled;
   int rows;
   DirtyRow* row;
   Mask* mask;
 };
 
-Dirty* dirty_new(Image* image, int x1, int y1, int x2, int y2, int tiled);
+Dirty* dirty_new(Image* image, int x1, int y1, int x2, int y2, bool tiled);
 Dirty* dirty_new_copy(Dirty* src);
 Dirty* dirty_new_from_differences(Image* image, Image* image_diff);
 void dirty_free(Dirty* dirty);