diff --git a/source/rozinante/draw.rs b/source/rozinante/draw.rs
index 6d70a8a..54292a5 100644
--- a/source/rozinante/draw.rs
+++ b/source/rozinante/draw.rs
@@ -25,22 +25,22 @@ pub trait DrawArea
    fn h(&self) -> Coord;
 
    /// Fills the entire screen with `cr`. Will also default all settings.
-   fn clear(&self, cr: impl Color);
+   fn clear(&mut self, cr: impl Color);
 
    /// Changes the width for lines. The default is `1`.
-   fn line_width(&self, width: u8);
+   fn line_width(&mut self, width: u8);
 
    /// Draws a line from `p1` to `p2` with color `cr`.
-   fn line(&self, p1: Point, p2: Point, cr: impl Color);
+   fn line(&mut self, p1: Point, p2: Point, cr: impl Color);
 
    /// Draws a rectangle `rect` of color `cr`.
-   fn rect(&self, rect: Rect, cr: impl Color);
+   fn rect(&mut self, rect: Rect, cr: impl Color);
 
    /// Draws the Unicode `text` at `pos` stroked with color `cr`.
-   fn text(&self, pos: Point, text: &str, cr: impl Color);
+   fn text(&mut self, pos: Point, text: &str, cr: impl Color);
 
    /// Draws `im` at `pos`, starting from the top left column.
-   fn image(&self, pos: Point, im: &Self::NativeImage);
+   fn image(&mut self, pos: Point, im: &Self::NativeImage);
 }
 
 /// A type capable of representing any coordinate on any axis.
diff --git a/source/tycho/interfaces.rs b/source/tycho/interfaces.rs
index d69ff5d..1eb8bbf 100644
--- a/source/tycho/interfaces.rs
+++ b/source/tycho/interfaces.rs
@@ -34,7 +34,7 @@ impl DrawArea for CrDrawArea
    fn w(&self) -> Coord {self.w}
    fn h(&self) -> Coord {self.h}
 
-   fn clear(&self, cr: impl Color)
+   fn clear(&mut self, cr: impl Color)
    {
       self.rect(Rect{x: 0, y: 0, w: self.w(), h: self.h()}, cr);
 
@@ -48,7 +48,7 @@ impl DrawArea for CrDrawArea
       }
    }
 
-   fn line_width(&self, width: u8)
+   fn line_width(&mut self, width: u8)
    {
       let width = f64::from(width);
 
@@ -57,7 +57,7 @@ impl DrawArea for CrDrawArea
       }
    }
 
-   fn line(&self, p1: Point, p2: Point, cr: impl Color)
+   fn line(&mut self, p1: Point, p2: Point, cr: impl Color)
    {
       let (r, g, b) = flt_color(cr);
 
@@ -75,7 +75,7 @@ impl DrawArea for CrDrawArea
       }
    }
 
-   fn rect(&self, rect: Rect, cr: impl Color)
+   fn rect(&mut self, rect: Rect, cr: impl Color)
    {
       let px = f64::from(rect.x);
       let py = f64::from(rect.y);
@@ -91,7 +91,7 @@ impl DrawArea for CrDrawArea
       }
    }
 
-   fn text(&self, pos: Point, text: &str, cr: impl Color)
+   fn text(&mut self, pos: Point, text: &str, cr: impl Color)
    {
       let (r, g, b) = flt_color(cr);
 
@@ -107,7 +107,7 @@ impl DrawArea for CrDrawArea
       }
    }
 
-   fn image(&self, pos: Point, im: &Self::NativeImage)
+   fn image(&mut self, pos: Point, im: &Self::NativeImage)
    {
       let x = f64::from(pos.0);
       let y = f64::from(pos.1);
diff --git a/source/tycho/main.rs b/source/tycho/main.rs
index d7cc23a..a5ec599 100644
--- a/source/tycho/main.rs
+++ b/source/tycho/main.rs
@@ -75,9 +75,9 @@ unsafe fn setup_draw_area(b: *mut GtkBuilder, edit: Rc<MapEditorRef>)
       gtk_adjustment_set_upper(rend.ay, h);
 
       let im = CrImage(rend.im_nomap);
-      let dr = CrDrawArea::new(ctx, w, h);
+      let mut dr = CrDrawArea::new(ctx, w, h);
 
-      rend.edit.borrow().draw(&dr, &im);
+      rend.edit.borrow().draw(&mut dr, &im);
 
       1
    }