diff --git a/bambu_run/mcp/shapes.py b/bambu_run/mcp/shapes.py
index 583a1f4..7c9fb30 100644
--- a/bambu_run/mcp/shapes.py
+++ b/bambu_run/mcp/shapes.py
@@ -108,7 +108,10 @@ def normalize_consumed(starting_percent, ending_percent, initial_weight_grams):
     fabricated zero (spec: 24/269 usage rows go negative; a -1 sentinel
     subtracted as a real value produces e.g. consumed=-101%).
     """
-    if starting_percent is None or starting_percent == -1 or ending_percent is None:
+    if (
+        starting_percent is None or starting_percent == -1
+        or ending_percent is None or ending_percent == -1
+    ):
         return None, None, "unreliable"
     consumed_percent = starting_percent - ending_percent
     if consumed_percent < 0:
diff --git a/tests/test_mcp_shapes.py b/tests/test_mcp_shapes.py
index 06094b0..8ff1e0a 100644
--- a/tests/test_mcp_shapes.py
+++ b/tests/test_mcp_shapes.py
@@ -109,6 +109,12 @@ def test_normalize_consumed_sentinel_start_goes_unreliable():
     assert normalize_consumed(-1, 100, initial_weight_grams=1000) == (None, None, "unreliable")
 
 
+def test_normalize_consumed_sentinel_end_goes_unreliable():
+    # symmetric case: ending_percent == -1 (no RFID reading at job end)
+    # must not fabricate a plausible-looking consumption figure
+    assert normalize_consumed(74, -1, initial_weight_grams=1000) == (None, None, "unreliable")
+
+
 @pytest.mark.django_db
 def test_resolve_printer_by_id():
     p = Printer.objects.create(name="RNL-H2C", model="H2C", is_active=True)