diff --git a/ext/plot.jl b/ext/plot.jl
index 4474b72..e292261 100644
--- a/ext/plot.jl
+++ b/ext/plot.jl
@@ -11,8 +11,8 @@ $(TYPEDEF)
 A leaf of a plot tree.
 """
 struct PlotLeaf <: AbstractPlotTreeElement
-    value::Tuple{Symbol, Integer}
-    PlotLeaf(value::Tuple{Symbol, Integer}) = new(value)
+    value::Tuple{Symbol, Int}
+    PlotLeaf(value::Tuple{Symbol, Int}) = new(value)
 end
 
 """
@@ -41,7 +41,7 @@ function __plot_time!(
     p::Union{Plots.Plot, Plots.Subplot},
     sol::OptimalControlSolution,
     s::Symbol,
-    i::Integer,
+    i::Int,
     time::Symbol;
     t_label,
     label::String,
@@ -103,7 +103,7 @@ Plot the i-th component of a vectorial function of time `f(t) ∈ Rᵈ` where `f
 function __plot_time(
     sol::OptimalControlSolution,
     s::Symbol,
-    i::Integer,
+    i::Int,
     time::Symbol;
     t_label,
     label::String,
@@ -187,7 +187,7 @@ $(TYPEDSIGNATURES)
 
 Plot a leaf.
 """
-function __plot_tree(leaf::PlotLeaf, depth::Integer; kwargs...)
+function __plot_tree(leaf::PlotLeaf, depth::Int; kwargs...)
     return Plots.plot()
 end
 
@@ -196,7 +196,7 @@ $(TYPEDSIGNATURES)
 
 Plot a node.
 """
-function __plot_tree(node::PlotNode, depth::Integer = 0; kwargs...)
+function __plot_tree(node::PlotNode, depth::Int = 0; kwargs...)
     #
     subplots = ()
     #
@@ -612,8 +612,8 @@ corresponding respectively to the argument `xx` and the argument `yy`.
 """
 @recipe function f(
     sol::OptimalControlSolution,
-    xx::Union{Symbol, Tuple{Symbol, Integer}},
-    yy::Union{Symbol, Tuple{Symbol, Integer}},
+    xx::Union{Symbol, Tuple{Symbol, Int}},
+    yy::Union{Symbol, Tuple{Symbol, Int}},
     time::Symbol = :default,
 )
 
@@ -629,8 +629,8 @@ end
 
 function recipe_label(
     sol::OptimalControlSolution,
-    xx::Union{Symbol, Tuple{Symbol, Integer}},
-    yy::Union{Symbol, Tuple{Symbol, Integer}},
+    xx::Union{Symbol, Tuple{Symbol, Int}},
+    yy::Union{Symbol, Tuple{Symbol, Int}},
 )
 
     #
@@ -661,7 +661,7 @@ Get the data for plotting.
 """
 function __get_data_plot(
     sol::OptimalControlSolution,
-    xx::Union{Symbol, Tuple{Symbol, Integer}};
+    xx::Union{Symbol, Tuple{Symbol, Int}};
     time::Symbol = :default,
 )
     T = time_grid(sol)
diff --git a/src/CTBase.jl b/src/CTBase.jl
index d9270be..59f7d8e 100644
--- a/src/CTBase.jl
+++ b/src/CTBase.jl
@@ -174,10 +174,10 @@ Type alias for a dimension. This is used to define the dimension of the state sp
 the costate space, the control space, etc.
 
 ```@example
-julia> const Dimension = Integer
+julia> const Dimension = Int
 ```
 """
-const Dimension = Integer
+const Dimension = Int
 
 #
 """
diff --git a/src/onepass.jl b/src/onepass.jl
index 4c2b86d..e533df9 100644
--- a/src/onepass.jl
+++ b/src/onepass.jl
@@ -25,7 +25,7 @@ $(TYPEDEF)
     x::Union{Symbol, Nothing} = nothing
     u::Union{Symbol, Nothing} = nothing
     aliases::OrderedDict{Symbol, Union{Real, Symbol, Expr}} = __init_aliases()
-    lnum::Integer = 0
+    lnum::Int = 0
     line::String = ""
     t_dep::Bool = false
 end
@@ -199,7 +199,7 @@ p_variable!(p, ocp, v, q; components_names = nothing, log = false) = begin
     v isa Symbol || return __throw("forbidden variable name: $v", p.lnum, p.line)
     p.v = v
     vv = QuoteNode(v)
-    qq = q isa Integer ? q : 9
+    qq = q isa Int ? q : 9
     for i ∈ 1:qq
         p.aliases[Symbol(v, ctindices(i))] = :($v[$i])
     end # make: v₁, v₂... if the variable is named v
@@ -283,7 +283,7 @@ p_state!(p, ocp, x, n; components_names = nothing, log = false) = begin
     x isa Symbol || return __throw("forbidden state name: $x", p.lnum, p.line)
     p.x = x
     xx = QuoteNode(x)
-    nn = n isa Integer ? n : 9
+    nn = n isa Int ? n : 9
     for i ∈ 1:nn
         p.aliases[Symbol(x, ctindices(i))] = :($x[$i])
     end # Make x₁, x₂... if the state is named x
@@ -314,7 +314,7 @@ p_control!(p, ocp, u, m; components_names = nothing, log = false) = begin
     u isa Symbol || return __throw("forbidden control name: $u", p.lnum, p.line)
     p.u = u
     uu = QuoteNode(u)
-    mm = m isa Integer ? m : 9
+    mm = m isa Int ? m : 9
     for i ∈ 1:mm
         p.aliases[Symbol(u, ctindices(i))] = :($u[$i])
     end # make: u₁, u₂... if the control is named u
@@ -341,7 +341,7 @@ end
 p_constraint!(p, ocp, e1, e2, e3, label = gensym(); log = false) = begin
     c_type = constraint_type(e2, p.t, p.t0, p.tf, p.x, p.u, p.v)
     log && println("constraint ($c_type): $e1 ≤ $e2 ≤ $e3,    ($label)")
-    label isa Integer && (label = Symbol(:eq, label))
+    label isa Int && (label = Symbol(:eq, label))
     label isa Symbol || return __throw("forbidden label: $label", p.lnum, p.line)
     llabel = QuoteNode(label)
     code = @match c_type begin
diff --git a/src/optimal_control_model-setters.jl b/src/optimal_control_model-setters.jl
index c21c96d..e7b8c5c 100644
--- a/src/optimal_control_model-setters.jl
+++ b/src/optimal_control_model-setters.jl
@@ -343,8 +343,8 @@ function time!(
     ocp::OptimalControlModel{<:TimeDependence, VT};
     t0::Union{Time, Nothing} = nothing,
     tf::Union{Time, Nothing} = nothing,
-    ind0::Union{Integer, Nothing} = nothing,
-    indf::Union{Integer, Nothing} = nothing,
+    ind0::Union{Int, Nothing} = nothing,
+    indf::Union{Int, Nothing} = nothing,
     name::Union{String, Symbol} = __time_name(),
 ) where {VT}
 
@@ -417,24 +417,24 @@ function time!(
             ocp.initial_time = t0
             ocp.final_time = tf
             ocp.time_name = name
-            ocp.initial_time_name = t0 isa Integer ? string(t0) : string(round(t0, digits = 2))
-            ocp.final_time_name = tf isa Integer ? string(tf) : string(round(tf, digits = 2))
+            ocp.initial_time_name = t0 isa Int ? string(t0) : string(round(t0, digits = 2))
+            ocp.final_time_name = tf isa Int ? string(tf) : string(round(tf, digits = 2))
         end
-        (::Nothing, ::Integer, ::Time, ::Nothing) => begin # (ind0, tf)
+        (::Nothing, ::Int, ::Time, ::Nothing) => begin # (ind0, tf)
             ocp.initial_time = Index(ind0)
             ocp.final_time = tf
             ocp.time_name = name
             ocp.initial_time_name = variable_components_names(ocp)[ind0]
-            ocp.final_time_name = tf isa Integer ? string(tf) : string(round(tf, digits = 2))
+            ocp.final_time_name = tf isa Int ? string(tf) : string(round(tf, digits = 2))
         end
-        (::Time, ::Nothing, ::Nothing, ::Integer) => begin # (t0, indf)
+        (::Time, ::Nothing, ::Nothing, ::Int) => begin # (t0, indf)
             ocp.initial_time = t0
             ocp.final_time = Index(indf)
             ocp.time_name = name
-            ocp.initial_time_name = t0 isa Integer ? string(t0) : string(round(t0, digits = 2))
+            ocp.initial_time_name = t0 isa Int ? string(t0) : string(round(t0, digits = 2))
             ocp.final_time_name = variable_components_names(ocp)[indf]
         end
-        (::Nothing, ::Integer, ::Nothing, ::Integer) => begin # (ind0, indf)
+        (::Nothing, ::Int, ::Nothing, ::Int) => begin # (ind0, indf)
             ocp.initial_time = Index(ind0)
             ocp.final_time = Index(indf)
             ocp.time_name = name
@@ -521,7 +521,7 @@ julia> constraint!(ocp, :mixed; f = (t, x, u, v) -> x[1]*v[2]-u, lb=0, ub=1)
 function constraint!(
     ocp::OptimalControlModel{T, V},
     type::Symbol;
-    rg::Union{OrdinalRange{<:Integer}, Index, Integer, Nothing} = nothing,
+    rg::Union{OrdinalRange{<:Int}, Index, Int, Nothing} = nothing,
     f::Union{Function, Nothing} = nothing,
     lb::Union{ctVector, Nothing} = nothing,
     ub::Union{ctVector, Nothing} = nothing,
diff --git a/src/optimal_control_solution-setters.jl b/src/optimal_control_solution-setters.jl
index 7cd6f6c..90d3800 100644
--- a/src/optimal_control_solution-setters.jl
+++ b/src/optimal_control_solution-setters.jl
@@ -16,7 +16,7 @@ function __OptimalControlSolution(
     costate::Union{Nothing, Function} = nothing,
     time_grid::Union{Nothing, TimesDisc} = nothing,
     variable::Union{Nothing, Variable} = nothing,
-    iterations::Union{Nothing, Integer} = nothing,
+    iterations::Union{Nothing, Int} = nothing,
     stopping::Union{Nothing, Symbol} = nothing,
     message::Union{Nothing, String} = nothing,
     success::Union{Nothing, Bool} = nothing,
@@ -103,7 +103,7 @@ function OptimalControlSolution(
     variable::Union{Nothing, Variable} = nothing,
     costate::Union{Nothing, Function} = nothing,
     time_grid::Union{Nothing, TimesDisc} = nothing,
-    iterations::Union{Nothing, Integer} = nothing,
+    iterations::Union{Nothing, Int} = nothing,
     stopping::Union{Nothing, Symbol} = nothing,
     message::Union{Nothing, String} = nothing,
     success::Union{Nothing, Bool} = nothing,
@@ -170,7 +170,7 @@ function OptimalControlSolution(
     variable::Variable,
     costate::Union{Nothing, Function} = nothing,
     time_grid::Union{Nothing, TimesDisc} = nothing,
-    iterations::Union{Nothing, Integer} = nothing,
+    iterations::Union{Nothing, Int} = nothing,
     stopping::Union{Nothing, Symbol} = nothing,
     message::Union{Nothing, String} = nothing,
     success::Union{Nothing, Bool} = nothing,
diff --git a/src/utils.jl b/src/utils.jl
index 009d038..d4bfb0e 100644
--- a/src/utils.jl
+++ b/src/utils.jl
@@ -3,7 +3,7 @@ $(TYPEDSIGNATURES)
 
 Return `i` ∈ [0, 9] as a subscript.
 """
-function ctindice(i::Integer)::Char
+function ctindice(i::Int)::Char
     if i < 0 || i > 9
         throw(IncorrectArgument("the indice must be between 0 and 9"))
     end
@@ -15,7 +15,7 @@ $(TYPEDSIGNATURES)
 
 Return `i` > 0 as a subscript.
 """
-function ctindices(i::Integer)::String
+function ctindices(i::Int)::String
     if i < 0
         throw(IncorrectArgument("the indice must be positive"))
     end
@@ -31,7 +31,7 @@ $(TYPEDSIGNATURES)
 
 Return `i` ∈ [0, 9] as an upperscript.
 """
-function ctupperscript(i::Integer)::Char
+function ctupperscript(i::Int)::Char
     if i < 0 || i > 9
         throw(IncorrectArgument("the upperscript must be between 0 and 9"))
     end
@@ -57,7 +57,7 @@ $(TYPEDSIGNATURES)
 
 Return `i` > 0 as an upperscript.
 """
-function ctupperscripts(i::Integer)::String
+function ctupperscripts(i::Int)::String
     if i < 0
         throw(IncorrectArgument("the upperscript must be positive"))
     end
@@ -165,7 +165,7 @@ $(TYPEDSIGNATURES)
 
 Transforms `x` to a Vector{<:Vector{<:ctNumber}}.
 """
-function vec2vec(x::Vector{<:ctNumber}, n::Integer)::Vector{<:Vector{<:ctNumber}}
+function vec2vec(x::Vector{<:ctNumber}, n::Int)::Vector{<:Vector{<:ctNumber}}
     y = [x[1:n]]
     for i = (n + 1):n:(length(x) - n + 1)
         y = vcat(y, [x[i:(i + n - 1)]])
@@ -203,7 +203,7 @@ Transforms `x` to a Vector{<:Vector{<:ctNumber}}.
 """
 function matrix2vec(
     x::Matrix{<:ctNumber},
-    dim::Integer = __matrix_dimension_stock(),
+    dim::Int = __matrix_dimension_stock(),
 )::Vector{<:Vector{<:ctNumber}}
     m, n = size(x)
     y = nothing
diff --git a/test/solution_test.jld2 b/test/solution_test.jld2
index 0c2791d..f613d1f 100644
Binary files a/test/solution_test.jld2 and b/test/solution_test.jld2 differ