diff --git a/test/gamma.c b/test/gamma.c
index fb7a774..aac14c8 100644
--- a/test/gamma.c
+++ b/test/gamma.c
@@ -87,7 +87,7 @@ int main(void)
                             cucul_get_canvas_height(cw), right, buffer);
 
         /* Draw something on the mask */
-        cucul_set_color(cv, CUCUL_COLOR_LIGHTGRAY, CUCUL_COLOR_BLACK);
+        cucul_set_color(mask, CUCUL_COLOR_LIGHTGRAY, CUCUL_COLOR_BLACK);
         cucul_clear_canvas(mask);
         cucul_set_color(mask, CUCUL_COLOR_WHITE, CUCUL_COLOR_WHITE);
         cucul_fill_ellipse(mask, (1.0 + sin(0.05 * (float)x))