diff --git a/preprocessor/ComputingTasks.cc b/preprocessor/ComputingTasks.cc
index 169333e65..b77520e6b 100644
--- a/preprocessor/ComputingTasks.cc
+++ b/preprocessor/ComputingTasks.cc
@@ -1359,7 +1359,7 @@ MarkovSwitchingStatement::MarkovSwitchingStatement(const OptionsList &options_li
 void
 MarkovSwitchingStatement::writeOutput(ostream &output, const string &basename) const
 {
-  OptionsList::num_options_t::const_iterator itChain, itState, itNOS, itDuration;
+  OptionsList::num_options_t::const_iterator itChain, itState, itNOR, itDuration;
 
   itChain = options_list.num_options.find("ms.chain");
   if (itChain == options_list.num_options.end())
@@ -1376,13 +1376,13 @@ MarkovSwitchingStatement::writeOutput(ostream &output, const string &basename) c
     }
 
   itState = options_list.num_options.find("ms.state");
-  itNOS = options_list.num_options.find("ms.number_of_states");
+  itNOR = options_list.num_options.find("ms.number_of_regimes");
   if (itState != options_list.num_options.end()
-      && itNOS == options_list.num_options.end())
+      && itNOR == options_list.num_options.end())
     output << "options_.ms.ms_chain(" << itChain->second << ").state(" << itState->second << ").duration = " << itDuration->second << ";" << endl;
   else if (itState == options_list.num_options.end()
-           && itNOS != options_list.num_options.end())
-    for (int i = 0; i < atoi(itNOS->second.c_str()); i++)
+           && itNOR != options_list.num_options.end())
+    for (int i = 0; i < atoi(itNOR->second.c_str()); i++)
       output << "options_.ms.ms_chain(" << itChain->second << ").state(" << i+1 << ").duration = " << itDuration->second << ";" << endl;
   else
     {
diff --git a/preprocessor/DynareBison.yy b/preprocessor/DynareBison.yy
index 00623ef13..ef3a2b988 100644
--- a/preprocessor/DynareBison.yy
+++ b/preprocessor/DynareBison.yy
@@ -156,7 +156,7 @@ class ParsingDriver;
 %token SBVAR TREND_VAR DEFLATOR GROWTH_FACTOR MS_IRF MS_VARIANCE_DECOMPOSITION
 %token MS_ESTIMATION MS_SIMULATION MS_COMPUTE_MDD MS_COMPUTE_PROBABILITIES MS_FORECAST
 %token SVAR_IDENTIFICATION EQUATION EXCLUSION LAG UPPER_CHOLESKY LOWER_CHOLESKY MONTHLY QUARTERLY
-%token MARKOV_SWITCHING CHAIN STATE DURATION NUMBER_OF_STATES
+%token MARKOV_SWITCHING CHAIN STATE DURATION NUMBER_OF_REGIMES
 %token SVAR COEFF COEFFICIENTS VARIANCES CONSTANTS EQUATIONS
 %token EXTERNAL_FUNCTION EXT_FUNC_NAME EXT_FUNC_NARGS FIRST_DERIV_PROVIDED SECOND_DERIV_PROVIDED
 %token SELECTED_VARIABLES_ONLY COVA_COMPUTE SIMULATION_FILE_TAG FILE_TAG
@@ -742,7 +742,7 @@ ms_options_list : ms_options_list COMMA ms_options
 ms_options : o_chain
            | o_state
            | o_duration
-           | o_number_of_states
+           | o_number_of_regimes
            ;
 
 svar : SVAR '(' svar_options_list ')' ';'
@@ -2226,7 +2226,7 @@ o_duration : DURATION EQUAL non_negative_number
            | DURATION EQUAL INF_CONSTANT
              { driver.option_num("ms.duration","Inf"); }
            ;
-o_number_of_states : NUMBER_OF_STATES EQUAL INT_NUMBER { driver.option_num("ms.number_of_states",$3); };
+o_number_of_regimes : NUMBER_OF_REGIMES EQUAL INT_NUMBER { driver.option_num("ms.number_of_regimes",$3); };
 o_coefficients : COEFFICIENTS { driver.option_str("ms.coefficients","svar_coefficients"); };
 o_variances : VARIANCES { driver.option_str("ms.variances","svar_variances"); };
 o_equations : EQUATIONS EQUAL vec_int
diff --git a/preprocessor/DynareFlex.ll b/preprocessor/DynareFlex.ll
index 626aad86b..e2b2a1708 100644
--- a/preprocessor/DynareFlex.ll
+++ b/preprocessor/DynareFlex.ll
@@ -505,7 +505,7 @@ string eofbuff;
 <DYNARE_STATEMENT,DYNARE_BLOCK>lower_cholesky {return token::LOWER_CHOLESKY;}
 <DYNARE_STATEMENT>chain {return token::CHAIN;}
 <DYNARE_STATEMENT>state {return token::STATE;}
-<DYNARE_STATEMENT>number_of_states {return token::NUMBER_OF_STATES;}
+<DYNARE_STATEMENT>number_of_regimes {return token::NUMBER_OF_REGIMES;}
 <DYNARE_STATEMENT>duration {return token::DURATION;}
 <DYNARE_STATEMENT>coefficients {return token::COEFFICIENTS;}
 <DYNARE_STATEMENT>variances {return token::VARIANCES;}
diff --git a/preprocessor/ParsingDriver.cc b/preprocessor/ParsingDriver.cc
index 4bc662010..6b0e65d22 100644
--- a/preprocessor/ParsingDriver.cc
+++ b/preprocessor/ParsingDriver.cc
@@ -1747,14 +1747,14 @@ ParsingDriver::markov_switching()
     error("The value passed to the chain option must be greater than zero.");
 
   it0 = options_list.num_options.find("ms.state");
-  it1 = options_list.num_options.find("ms.number_of_states");
+  it1 = options_list.num_options.find("ms.number_of_regimes");
   if ((it0 == options_list.num_options.end())
       && (it1 == options_list.num_options.end()))
-    error("Either a state option or a number_of_states option must be passed to the markov_switching statement.");
+    error("Either a state option or a number_of_regimes option must be passed to the markov_switching statement.");
 
   if ((it0 != options_list.num_options.end())
       && (it1 != options_list.num_options.end()))
-    error("You cannot pass both a state option and a number_of_states option to the markov_switching statement.");
+    error("You cannot pass both a state option and a number_of_regimes option to the markov_switching statement.");
 
   if (it0 != options_list.num_options.end())
     if (atoi(it0->second.c_str()) <= 0)
@@ -1762,7 +1762,7 @@ ParsingDriver::markov_switching()
 
   if (it1 != options_list.num_options.end())
     if (atoi(it1->second.c_str()) <= 0)
-      error("The value passed to the number_of_states option must be greater than zero.");
+      error("The value passed to the number_of_regimes option must be greater than zero.");
 
   string infStr("Inf");
   it0 = options_list.num_options.find("ms.duration");
diff --git a/tests/ms-sbvar/test_ms_variances.mod b/tests/ms-sbvar/test_ms_variances.mod
index acf3e827c..6f6d2477b 100644
--- a/tests/ms-sbvar/test_ms_variances.mod
+++ b/tests/ms-sbvar/test_ms_variances.mod
@@ -6,7 +6,7 @@ svar_identification;
 lower_cholesky;
 end;
 
-markov_switching(chain=1,number_of_states=2,duration=2.5);
+markov_switching(chain=1,number_of_regimes=2,duration=2.5);
 
 svar(variances, chain=1);
 
diff --git a/tests/ms-sbvar/test_ms_variances_repeated_runs.mod b/tests/ms-sbvar/test_ms_variances_repeated_runs.mod
index 35f64ab84..a4ffc6fb0 100644
--- a/tests/ms-sbvar/test_ms_variances_repeated_runs.mod
+++ b/tests/ms-sbvar/test_ms_variances_repeated_runs.mod
@@ -6,7 +6,7 @@ svar_identification;
 lower_cholesky;
 end;
 
-markov_switching(chain=1,number_of_states=2,duration=2.5);
+markov_switching(chain=1,number_of_regimes=2,duration=2.5);
 
 svar(variances, chain=1);