diff --git a/matlab/evaluate_posterior_kernel.m b/matlab/evaluate_posterior_kernel.m
index c3eb15983..fa34b657a 100644
--- a/matlab/evaluate_posterior_kernel.m
+++ b/matlab/evaluate_posterior_kernel.m
@@ -36,6 +36,7 @@ function lpkern = evaluate_posterior_kernel(parameters,llik)
   
     [ldens,parameters] = evaluate_prior(parameters);
     if nargin==1
+        clear('priordens')% Persistent variables in priordens have to be cleared!
         llik = evaluate_likelihood(parameters);
     end
     lpkern = ldens+llik;
\ No newline at end of file