diff --git a/libc/stdio/ftell.c b/libc/stdio/ftell.c
index b7d449e..9f850ee 100644
--- a/libc/stdio/ftell.c
+++ b/libc/stdio/ftell.c
@@ -45,20 +45,22 @@
 
 	if (fp->_seek == NULL) {
 		errno = ESPIPE;			/* historic practice */
-		return ((off_t)-1);
+		pos = -1;
+                goto out;
 	}
 
 	/*
 	 * Find offset of underlying I/O object, then
 	 * adjust for buffered bytes.
 	 */
+        FLOCKFILE(fp);
 	__sflush(fp);		/* may adjust seek offset on append stream */
 	if (fp->_flags & __SOFF)
 		pos = fp->_offset;
 	else {
 		pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR);
-		if (pos == -1L)
-			return (pos);
+		if (pos == -1)
+			goto out;
 	}
 	if (fp->_flags & __SRD) {
 		/*
@@ -77,6 +79,7 @@
 		 */
 		pos += fp->_p - fp->_bf._base;
 	}
+out:	FUNLOCKFILE(fp);
 	return (pos);
 }