diff --git a/lrzip_private.h b/lrzip_private.h
index 2b8b241..1744ecc 100644
--- a/lrzip_private.h
+++ b/lrzip_private.h
@@ -373,6 +373,8 @@ struct rzip_control {
 	uchar *salt_pass;
 	int salt_pass_len;
 	uchar *hash;
+
+	pthread_mutex_t control_lock;
 	unsigned char eof;
 	unsigned char magic_written;
 
diff --git a/rzip.c b/rzip.c
index 46fea5e..907b83f 100644
--- a/rzip.c
+++ b/rzip.c
@@ -918,6 +918,7 @@ bool rzip_fd(rzip_control *control, int fd_in, int fd_out)
 	double chunkmbs;
 	i64 free_space;
 
+	init_mutex(control, &control->control_lock);
 	if (!NO_MD5)
 		md5_init_ctx(&control->ctx);
 	init_mutex(control, &control->cksumlock);