--- Libc/Libc-763.13/stdio/FreeBSD/wsetup.c
+++ Libc/Libc-1158.20.4/stdio/FreeBSD/wsetup.c
@@ -51,8 +51,7 @@
 	FILE *fp;
 {
 	/* make sure stdio is set up */
-	if (!__sdidinit)
-		__sinit();
+	pthread_once(&__sdidinit, __sinit);
 
 	/*
 	 * If we are not writing, we had better be reading and writing.