diff --git a/DynareBison.yy b/DynareBison.yy
index 801aa600de6f1008b2df21b8f641ddfb46fe9ded..97c4551494e959cf75011fbf9fc6d87884295116 100644
--- a/DynareBison.yy
+++ b/DynareBison.yy
@@ -113,7 +113,7 @@ class ParsingDriver;
 %token CPF_WEIGHTS AMISANOTRISTANI MURRAYJONESPARSLOW WRITE_EQUATION_TAGS
 %token NONLINEAR_FILTER_INITIALIZATION FILTER_ALGORITHM PROPOSAL_APPROXIMATION CUBATURE UNSCENTED MONTECARLO DISTRIBUTION_APPROXIMATION
 %token <string_val> NAME
-%token USE_PENALIZED_OBJECTIVE_FOR_HESSIAN INIT_STATE RESCALE_PREDICTION_ERROR_COVARIANCE GENERATE_IRFS
+%token USE_PENALIZED_OBJECTIVE_FOR_HESSIAN INIT_STATE FAST_REALTIME RESCALE_PREDICTION_ERROR_COVARIANCE GENERATE_IRFS
 %token NAN_CONSTANT NO_STATIC NOBS NOCONSTANT NODISPLAY NOCORR NODIAGNOSTIC NOFUNCTIONS NO_HOMOTOPY
 %token NOGRAPH POSTERIOR_NOGRAPH POSTERIOR_GRAPH NOMOMENTS NOPRINT NORMAL_PDF SAVE_DRAWS STDERR_MULTIPLES DIAGONAL_ONLY
 %token OBSERVATION_TRENDS OPTIM OPTIM_WEIGHTS ORDER OSR OSR_PARAMS MAX_DIM_COVA_GROUP ADVANCED OUTFILE OUTVARS OVERWRITE
@@ -2687,6 +2687,7 @@ realtime_shock_decomposition_option : o_parameter_set
                                     | o_shock_decomposition_presample
                                     | o_shock_decomposition_forecast
                                     | o_save_realtime
+                                    | o_fast_realtime
                                     ;
 
 plot_shock_decomposition_options_list : plot_shock_decomposition_option COMMA plot_shock_decomposition_options_list
@@ -3095,6 +3096,7 @@ o_init_state : INIT_STATE EQUAL INT_NUMBER { driver.option_num("shock_decomp.ini
 o_shock_decomposition_presample : PRESAMPLE EQUAL INT_NUMBER { driver.option_num("shock_decomp.presample", $3); };
 o_shock_decomposition_forecast : FORECAST EQUAL INT_NUMBER { driver.option_num("shock_decomp.forecast", $3); };
 o_save_realtime : SAVE_REALTIME EQUAL vec_int { driver.option_vec_int("shock_decomp.save_realtime", $3); };
+o_fast_realtime : FAST_REALTIME { driver.option_num("shock_decomp.fast_realtime", "1"); };
 o_nodisplay : NODISPLAY { driver.option_num("nodisplay","1"); };
 o_psd_nodisplay : NODISPLAY { driver.option_num("plot_shock_decomp.nodisplay","1"); };
 o_graph_format : GRAPH_FORMAT EQUAL allowed_graph_formats
diff --git a/DynareFlex.ll b/DynareFlex.ll
index c35b8a011a11dfd1cd2649cb3a925e7de111ca3f..db43397d6766ba49f04440398f2dfb69860aa572 100644
--- a/DynareFlex.ll
+++ b/DynareFlex.ll
@@ -584,6 +584,7 @@ DATE -?[0-9]+([YyAa]|[Mm]([1-9]|1[0-2])|[Qq][1-4]|[Ww]([1-9]{1}|[1-4][0-9]|5[0-2
 <DYNARE_STATEMENT>controlled_varexo {return token::CONTROLLED_VAREXO; }
 <DYNARE_STATEMENT>parameter_set {return token::PARAMETER_SET; }
 <DYNARE_STATEMENT>init_state {return token::INIT_STATE; }
+<DYNARE_STATEMENT>fast_realtime {return token::FAST_REALTIME; }
 <DYNARE_STATEMENT>save_realtime {return token::SAVE_REALTIME;}
 <DYNARE_STATEMENT>detail_plot {return token::DETAIL_PLOT;}
 <DYNARE_STATEMENT>interactive {return token::INTERACTIVE;}