diff --git a/samples/mandelbrot.c b/samples/mandelbrot.c
index 595bcfbbb..519f3d823 100644
--- a/samples/mandelbrot.c
+++ b/samples/mandelbrot.c
@@ -31,6 +31,7 @@
 /* Workaround missing clock stuff */
 #ifdef __APPLE2__
 #  define clock()       0
+#  undef  CLK_TCK
 #  define CLK_TCK       1
 #endif