diff --git a/src/cairo-skiplist.c b/src/cairo-skiplist.c
index 5c2c477ed..776e7e787 100644
--- a/src/cairo-skiplist.c
+++ b/src/cairo-skiplist.c
@@ -25,6 +25,8 @@
 
 #include "cairo-skiplist-private.h"
 
+#include <strings.h> /* ffs() */
+
 #define ELT_DATA(elt) (void *)	((char*) (elt) - list->data_size)
 #define NEXT_TO_ELT(next)	(skip_elt_t *) ((char *) (next) - offsetof (skip_elt_t, next))