-XBT_PUBLIC(int) asprintf (char **ptr, const char *fmt, /*args*/ ...) _XBT_GNUC_PRINTF(2,3);
-XBT_PUBLIC(int) vasprintf (char **ptr, const char *fmt, va_list ap);
+#ifndef __USE_GNU /* do not redeclare existing headers */
+ XBT_PUBLIC(int) asprintf (char **ptr, const char *fmt, /*args*/ ...) _XBT_GNUC_PRINTF(2,3);
+ XBT_PUBLIC(int) vasprintf (char **ptr, const char *fmt, va_list ap);
+#endif