diff --git a/src/tlo/lm.py b/src/tlo/lm.py
index e099714850..a7538a1a7a 100644
--- a/src/tlo/lm.py
+++ b/src/tlo/lm.py
@@ -385,7 +385,7 @@ def predict(
         rng: Optional[np.random.RandomState] = None,
         squeeze_single_row_output=True,
         **kwargs
-    ) -> pd.Series:
+    ) -> Union[pd.Series, np.bool_]:
         """Evaluate linear model output for a given set of input data.
 
         :param df: The input ``DataFrame`` containing the input data to evaluate the
@@ -396,7 +396,8 @@ def predict(
           output directly returned.
         :param squeeze_single_row_output: If ``rng`` argument is not ``None`` and this
           argument is set to ``True``, the output for a ``df`` input with a single-row
-          will be a scalar boolean value rather than a boolean ``Series``.
+          will be a scalar boolean value rather than a boolean ``Series``, if set to
+          ``False``, the output will always be a ``Series``.
         :param **kwargs: Values for any external variables included in model
           predictors.
         """