diff -Naur qhull-2003.1.orig/src/io.c qhull-2003.1/src/io.c
--- qhull-2003.1.orig/src/io.c	2014-04-14 18:38:38.000000000 +0200
+++ qhull-2003.1/src/io.c	2014-04-14 18:42:15.924000000 +0200
@@ -2166,7 +2166,7 @@
     qh_memfree (point, qh normal_size);
   qh_settempfree(&points);
   qh_settempfree(&vertices);
-  fprintf(fp, endfmt);
+  fprintf(fp, "%s", endfmt);
 } /* printfacet3math */