diff --git a/src/tempe/markers.py b/src/tempe/markers.py
index aa2dc61..e3caee5 100644
--- a/src/tempe/markers.py
+++ b/src/tempe/markers.py
@@ -44,17 +44,17 @@ def draw(self, buffer, x=0, y=0):
                 buffer.hline(px - size // 2, py, size, color)
                 buffer.vline(px, py - size // 2, size, color)
             elif marker == Marker.CROSS:
-                d = 17 * size // 48  # very rough approximation of 1/(2*sqrt(2))
+                d = (17 * size // 48) + 1  # very rough approximation of 1/(2*sqrt(2))
                 buffer.line(px - d, py - d, px + d, py + d, color)
                 buffer.line(px - d, py + d, px + d, py - d, color)
             elif isinstance(marker, str):
                 buffer.text(marker, px - 4, py - 4, color)
             elif isinstance(marker, framebuf.FrameBuffer):
                 # assume 1-bit framebuffer - no way to test!
-                palette[1] = color
+                palette_buf[1] = color
                 buffer.blit(marker, px, py, BLIT_KEY_RGB565, palette)
             elif isinstance(marker, array):
-                buffer.polgon(px, py, marker, color, fill=True)
+                buffer.poly(px, py, marker, color, True)
 
     def update(self, geometry=None, colors=None, markers=None):
         if geometry is not None:
@@ -64,3 +64,16 @@ def update(self, geometry=None, colors=None, markers=None):
         if markers is not None:
             self.markers = markers
         super().update()
+
+    def _bounds(self):
+        max_x = -0x7fff
+        min_x = 0x7fff
+        max_y = -0x7fff
+        min_y = 0x7fff
+        for geometry in self.geometry:
+            max_x = max(max_x, geometry[0] + abs(geometry[2]))
+            min_x = min(min_x, geometry[0] - abs(geometry[2]))
+            max_y = max(max_y, geometry[1] + abs(geometry[2]))
+            min_y = min(min_y, geometry[1] - abs(geometry[2]))
+
+        return (min_x - 1, min_y - 1, max_x - min_x + 2, max_y - min_y + 2)