diff --git a/preprocessor/DynareBison.yy b/preprocessor/DynareBison.yy
index c6bd203b43833bcf3e2d5302ecd5c85011156518..d225c19727dbf48fbc0060d5b96cede537ad4f5a 100644
--- a/preprocessor/DynareBison.yy
+++ b/preprocessor/DynareBison.yy
@@ -1742,6 +1742,7 @@ osr_options : stoch_simul_primary_options
             | o_osr_maxit
             | o_osr_tolf
             | o_opt_algo
+            | o_optim
             ;
 
 osr : OSR ';'