diff --git a/devices/common/scsi/scsibus.cpp b/devices/common/scsi/scsibus.cpp
index 1703af3..cc56337 100644
--- a/devices/common/scsi/scsibus.cpp
+++ b/devices/common/scsi/scsibus.cpp
@@ -286,12 +286,22 @@ int ScsiBus::target_xfer_data() {
 
 void ScsiBus::target_next_step()
 {
-    this->devices[this->target_id]->next_step();
+    if (target_id < 0) {
+        LOG_F(ERROR, "%s: target_id is not set yet.", this->get_name().c_str());
+    }
+    else {
+        this->devices[this->target_id]->next_step();
+    }
 }
 
 bool ScsiBus::negotiate_xfer(int& bytes_in, int& bytes_out)
 {
-    this->devices[this->target_id]->prepare_xfer(this, bytes_in, bytes_out);
+    if (target_id < 0) {
+        LOG_F(ERROR, "%s: target_id is not set yet.", this->get_name().c_str());
+    }
+    else {
+        this->devices[this->target_id]->prepare_xfer(this, bytes_in, bytes_out);
+    }
 
     return true;
 }