diff --git a/hardware/serial-dmm/api.c b/hardware/serial-dmm/api.c
index 8a2d7be2..be240e23 100644
--- a/hardware/serial-dmm/api.c
+++ b/hardware/serial-dmm/api.c
@@ -151,6 +151,10 @@ static int clear_instances(void)
 	struct dev_context *devc;
 	GSList *l;
 
+	/* di is not necessarily initialized */
+	if (!di)
+		return SR_OK;
+
 	if (!(drvc = di->priv))
 		return SR_OK;