diff --git a/preprocessor b/preprocessor
index bf89cedd88eef94b9e45ebf7a0a43574a1e4a16a..84d57393dc3972f1c61be9f9047ecd517319a318 160000
--- a/preprocessor
+++ b/preprocessor
@@ -1 +1 @@
-Subproject commit bf89cedd88eef94b9e45ebf7a0a43574a1e4a16a
+Subproject commit 84d57393dc3972f1c61be9f9047ecd517319a318
diff --git a/tests/on-the-fly/ex3.mod b/tests/on-the-fly/ex3.mod
index d1f02a459e65b6ed9fdf4e682b1a6fafe45f814f..d36affb65816eb0ad7672f1bbbf6032faaf8431f 100644
--- a/tests/on-the-fly/ex3.mod
+++ b/tests/on-the-fly/ex3.mod
@@ -31,10 +31,10 @@ if ~isequal(length(intersect(M_.endo_names, {'c'; 'y'; 'k'; 'b'; 'a'; 'h'})), 6)
    error('Endogenous variables are wrong.')
 end
 
-if isfield(M_, 'param_names')
+if length(M_.param_names) > 0
    error('Parameters are wrong.')
 end
 
 if ~isequal(length(intersect(M_.exo_names, {'e'; 'u'; 'theta'; 'psi'; 'alpha'; 'beta'; 'delta'; 'rho'; 'tau'})), 9)
    error('Exogenous variables are wrong.')
-end
\ No newline at end of file
+end
diff --git a/tests/on-the-fly/ex4.mod b/tests/on-the-fly/ex4.mod
index 601699e95666ed900b58f62e574e18874ad43b45..ccf90f9c1cf762accb26199321c57d319517dd9f 100644
--- a/tests/on-the-fly/ex4.mod
+++ b/tests/on-the-fly/ex4.mod
@@ -30,10 +30,10 @@ if ~isequal(length(intersect(M_.endo_names, {'c'; 'y'; 'k'; 'b'; 'a'})), 5)
    error('Endogenous variables are wrong.')
 end
 
-if isfield(M_, 'param_names')
+if length(M_.param_names) > 0
    error('Parameters are wrong.')
 end
 
 if ~isequal(length(intersect(M_.exo_names, {'e'; 'u'; 'h'; 'alpha'; 'beta'; 'delta'; 'rho'; 'tau'})), 8)
    error('Exogenous variables are wrong.')
-end
\ No newline at end of file
+end
diff --git a/tests/on-the-fly/ex5.mod b/tests/on-the-fly/ex5.mod
index 4129465a7f468000ead2308de4cdb30cf6150082..7d28629b6e00def2730f5d3cc312037037737973 100644
--- a/tests/on-the-fly/ex5.mod
+++ b/tests/on-the-fly/ex5.mod
@@ -31,6 +31,6 @@ if ~isequal(length(intersect(M_.endo_names, {'D'; 'S'; 'p'})), 3)
    error('Endogenous variables are wrong.')
 end
 
-if isfield(M_, 'exo_names')
+if length(M_.exo_names) > 0
    error('Exogenous variables are wrong.')
 end