diff --git a/device-types/APC/BX750MI-GR.yaml b/device-types/APC/BX750MI-GR.yaml
index c8b8afdd..6203844e 100644
--- a/device-types/APC/BX750MI-GR.yaml
+++ b/device-types/APC/BX750MI-GR.yaml
@@ -15,7 +15,7 @@ comments: '[BX750MI-GR Datasheet by Kolyan](https://www.apc.com/kz/ru/product/BX
 front-ports:
   - name: IN
     type: 8p8c
-    rear_port: '1'
+    rear_port: OUT
     rear_port_position: 1
 rear-ports:
   - name: OUT
diff --git a/tests/definitions_test.py b/tests/definitions_test.py
index 09cae823..f7f47996 100644
--- a/tests/definitions_test.py
+++ b/tests/definitions_test.py
@@ -193,6 +193,29 @@ def test_definitions(file_path, schema, change_type):
         # A module
         this_device = ModuleType(definition, file_path, change_type)
 
+    # Validate that front-ports reference existing rear-ports
+    if this_device.isDevice:
+        rear_ports = definition.get("rear-ports", []) or []
+        front_ports = definition.get("front-ports", []) or []
+
+        rear_port_names = {
+            rp.get("name") for rp in rear_ports if isinstance(rp, dict)
+        }
+
+        for fp in front_ports:
+            if not isinstance(fp, dict):
+                continue
+
+            rear_port_ref = fp.get("rear_port")
+
+            if rear_port_ref and rear_port_ref not in rear_port_names:
+                pytest.fail(
+                    f"{file_path}: front-port '{fp.get('name')}' references "
+                    f"rear_port '{rear_port_ref}', but no such rear-port exists. "
+                    f"Defined rear-ports: {sorted(rear_port_names)}",
+                    pytrace=False,
+                )
+
     # Verify the slug is valid, only if the definition type is a Device
     if this_device.isDevice:
         assert this_device.verify_slug(KNOWN_SLUGS), pytest.fail(this_device.failureMessage, False)