diff --git a/DynareBison.yy b/DynareBison.yy
index 855020c1137c83b89258e9cb6384c0306dbd5d90..6d056c7c5ecc4aebc3d1dca81a416726b9b536bc 100644
--- a/DynareBison.yy
+++ b/DynareBison.yy
@@ -1754,7 +1754,7 @@ o_constant : CONSTANT { driver.option_num("noconstant", "0"); };
 o_noconstant : NOCONSTANT { driver.option_num("noconstant", "1"); };
 o_mh_recover : MH_RECOVER { driver.option_num("mh_recover", "1"); };
 o_diffuse_filter: DIFFUSE_FILTER {driver.option_num("diffuse_filter", "1"); };
-o_plot_priors: PLOT_PRIORS {driver.option_num("plot_priors", "1"); };
+o_plot_priors: PLOT_PRIORS EQUAL INT_NUMBER {driver.option_num("plot_priors", $3); };
 o_aim_solver: AIM_SOLVER {driver.option_num("aim_solver", "1"); };
 o_partial_information : PARTIAL_INFORMATION {driver.option_num("partial_information", "1"); };