diff --git a/source/_ext/cookbook/globals_.py b/source/_ext/cookbook/globals_.py
index f628e1196..11ede26ff 100644
--- a/source/_ext/cookbook/globals_.py
+++ b/source/_ext/cookbook/globals_.py
@@ -94,6 +94,7 @@
 OPTIONAL_NOTEBOOKS: list[str] = [
     # ".*/experimental/.*",
     "openforcefield/openff-interchange/experimental/openmmforcefields/gaff.ipynb",
+    "openforcefield/openff-interchange/ligand_in_water/ligand_in_water.ipynb",
 ]
 """
 Notebooks whose execution failure will not cause notebook processing to fail.