2 files changed, 10 insertions, 0 deletions

diff --git a/lib/libc/stdio/local.h b/lib/libc/stdio/local.h
index 4f5242a917d1..3e498d36d4fc 100644
--- a/lib/libc/stdio/local.h
+++ b/lib/libc/stdio/local.h
@@ -103,3 +103,10 @@ struct __sFILEX {
 	free((char *)(fp)->_lb._base); \
 	(fp)->_lb._base = NULL; \
 }
+
+#define	INITEXTRA(fp) { \
+	(fp)->_extra->_up = NULL; \
+	(fp)->_extra->fl_mutex = PTHREAD_MUTEX_INITIALIZER; \
+	(fp)->_extra->fl_owner = NULL; \
+	(fp)->_extra->fl_count = 0; \
+}
diff --git a/lib/libc/stdio/sscanf.c b/lib/libc/stdio/sscanf.c
index 2ed797efdf90..c8877883bbc6 100644
--- a/lib/libc/stdio/sscanf.c
+++ b/lib/libc/stdio/sscanf.c
@@ -77,6 +77,7 @@ sscanf(str, fmt, va_alist)
 {
 	int ret;
 	va_list ap;
+	struct __sFILEX extra;
 	FILE f;
 
 	f._file = -1;
@@ -86,6 +87,8 @@ sscanf(str, fmt, va_alist)
 	f._read = eofread;
 	f._ub._base = NULL;
 	f._lb._base = NULL;
+	f._extra = &extra;
+	INITEXTRA(&f);
 #if __STDC__
 	va_start(ap, fmt);
 #else