1 files changed, 14 insertions, 1 deletions

diff --git a/lib/libc/stdio/putc.c b/lib/libc/stdio/putc.c
index c18353b7044a..f1d42b11454b 100644
--- a/lib/libc/stdio/putc.c
+++ b/lib/libc/stdio/putc.c
@@ -39,15 +39,28 @@ static char sccsid[] = "@(#)putc.c	8.1 (Berkeley) 6/4/93";
 #endif /* LIBC_SCCS and not lint */
 
 #include <stdio.h>
+#ifdef _THREAD_SAFE
+#include <pthread.h>
+#include "pthread_private.h"
+#endif
 
 /*
  * A subroutine version of the macro putc.
  */
 #undef putc
 
+int
 putc(c, fp)
 	int c;
 	register FILE *fp;
 {
-	return (__sputc(c, fp));
+	int retval;
+#ifdef _THREAD_SAFE
+	_thread_flockfile(fp,__FILE__,__LINE__);
+#endif
+	retval = __sputc(c, fp);
+#ifdef _THREAD_SAFE
+	_thread_funlockfile(fp);
+#endif
+	return (retval);
 }