diff --git a/bambi/interpret/effects.py b/bambi/interpret/effects.py
index 26fee0794..85bd3e212 100644
--- a/bambi/interpret/effects.py
+++ b/bambi/interpret/effects.py
@@ -1,7 +1,7 @@
 # pylint: disable=ungrouped-imports
 from dataclasses import dataclass, field
 import itertools
-from typing import Dict, Union
+from typing import Dict, Tuple, Union
 
 import arviz as az
 import numpy as np
@@ -413,7 +413,7 @@ def predictions(
     prob=None,
     transforms=None,
     return_posterior: bool = False,
-) -> pd.DataFrame:
+) -> Union[pd.DataFrame, Tuple[pd.DataFrame, pd.DataFrame]]:
     """Compute Conditional Adjusted Predictions
 
     Parameters
@@ -531,7 +531,7 @@ def predictions(
     predictions_summary[response.upper_bound_name] = y_hat_bounds[1]
 
     if return_posterior:
-        return predictions_summary, get_posterior(response.name_obs, idata, cap_data)
+        return (predictions_summary, get_posterior(response.name_obs, idata, cap_data))
 
     return predictions_summary
 
@@ -547,7 +547,7 @@ def comparisons(
     prob: Union[float, None] = None,
     transforms: Union[dict, None] = None,
     return_posterior: bool = False,
-) -> pd.DataFrame:
+) -> Union[pd.DataFrame, Tuple[pd.DataFrame, pd.DataFrame]]:
     """Compute Conditional Adjusted Comparisons
 
     Parameters
@@ -669,7 +669,7 @@ def comparisons(
         comparisons_summary = predictive_difference.average_by(variable=average_by)
 
     if return_posterior:
-        return comparisons_summary, get_posterior(response.name_obs, idata, comparisons_data)
+        return (comparisons_summary, get_posterior(response.name_obs, idata, comparisons_data))
 
     return comparisons_summary
 
@@ -686,7 +686,7 @@ def slopes(
     prob: Union[float, None] = None,
     transforms: Union[dict, None] = None,
     return_posterior: bool = False,
-) -> pd.DataFrame:
+) -> Union[pd.DataFrame, Tuple[pd.DataFrame, pd.DataFrame]]:
     """Compute Conditional Adjusted Slopes
 
     Parameters
@@ -815,6 +815,6 @@ def slopes(
         slopes_summary = predictive_difference.average_by(variable=average_by)
 
     if return_posterior:
-        return slopes_summary, get_posterior(response.name_obs, idata, slopes_data)
+        return (slopes_summary, get_posterior(response.name_obs, idata, slopes_data))
 
     return slopes_summary