diff --git a/block.c b/block.c
index 9b5e9e11fe..ff2795b1e9 100644
--- a/block.c
+++ b/block.c
@@ -2859,13 +2859,8 @@ int bdrv_img_create(const char *filename, const char *fmt,
     if (get_option_parameter(param, BLOCK_OPT_SIZE)->value.n == -1) {
         if (backing_file && backing_file->value.s) {
             uint64_t size;
-            const char *fmt = NULL;
             char buf[32];
 
-            if (backing_fmt && backing_fmt->value.s) {
-                fmt = backing_fmt->value.s;
-            }
-
             bs = bdrv_new("");
 
             ret = bdrv_open(bs, backing_file->value.s, flags, drv);