diff --git a/vega/vega_interface.py b/vega/vega_interface.py
index 9427647..db2a31b 100644
--- a/vega/vega_interface.py
+++ b/vega/vega_interface.py
@@ -398,7 +398,7 @@ def log_lik(self, params=None, direct_pk=None):
                 log_norm -= 0.5 * self.data[name].data_size * np.log(2 * np.pi)
 
             # Compute log lik
-            log_lik = log_norm - log_det - 0.5 * (chi2 + prior_chi2)
+            log_lik = log_norm - log_det - 0.5 * chi2
 
         # Add priors normalization
         for prior in self.priors.values():