1 files changed, 3 insertions, 0 deletions
diff --git a/src/sys/os/os_iotap.c b/src/sys/os/os_iotap.c
index 238acfe..54d1157 100644
--- a/src/sys/os/os_iotap.c
+++ b/src/sys/os/os_iotap.c
@@ -130,6 +130,9 @@ iotap_mux(const char *name, struct iotap_msg *msg)
     ops = desc.ops;
     switch (msg->opcode) {
     case IOTAP_OPC_READ:
+        if (ops->read == NULL) {
+            return -ENOTSUP;
+        }
         return ops->read(&desc, msg->buf, msg->len);
     }