diff --git a/docs/noise.ipynb b/docs/noise.ipynb
index fe39fd8839b..e8eaa60a5ab 100644
--- a/docs/noise.ipynb
+++ b/docs/noise.ipynb
@@ -401,7 +401,7 @@
    "source": [
     "There are two configurable channel types for channels not defined in `cirq.ops.common_channels`: `MixedUnitaryChannel` and `KrausChannel`.\n",
     "\n",
-    "`MixedUnitaryChannel` takes a list of `(probability, unitary)` tuples and uses it to define the `_matrix_` method.\n",
+    "`MixedUnitaryChannel` takes a list of `(probability, unitary)` tuples and uses it to define the `_mixture_` method.\n",
     "\n",
     "`KrausChannel` takes a list of Kraus operators and uses it to define the `_channel` method.\n",
     "\n",