diff --git a/Sources/Stim.Model/Game.cs b/Sources/Stim.Model/Game.cs
index 8c805b9..bb29b01 100644
--- a/Sources/Stim.Model/Game.cs
+++ b/Sources/Stim.Model/Game.cs
@@ -11,9 +11,9 @@ namespace Model
         public string Name
         {
             get { return name; }
-            set
+            private set
             {
-                if (value == null || string.IsNullOrWhiteSpace(value)) return;
+                if (string.IsNullOrWhiteSpace(value)) return;
                 name = value;
             }
         }
@@ -23,9 +23,9 @@ namespace Model
         public string Description
         {
             get { return description; }
-            set
+            private set
             {
-                if (value == null || string.IsNullOrWhiteSpace(value)) return;
+                if (string.IsNullOrWhiteSpace(value)) return;
                 description = value;
             }
         }
@@ -35,7 +35,7 @@ namespace Model
         public int Year
         {
             get { return year; }
-            set
+            private set
             {
                 if (value < 1957 || value > 2023) return;
                 year = value;
@@ -49,7 +49,7 @@ namespace Model
             get => cover;
             set
             {
-                if (value == null || string.IsNullOrWhiteSpace(value)) return;
+                if (string.IsNullOrWhiteSpace(value)) return;
                 cover = value;
             }
         }
diff --git a/Sources/Stim.Model/Review.cs b/Sources/Stim.Model/Review.cs
index 434c10b..75ee176 100644
--- a/Sources/Stim.Model/Review.cs
+++ b/Sources/Stim.Model/Review.cs
@@ -34,7 +34,7 @@ namespace Model
             }
             private set
             {
-                if (text == "") return;
+                if (string.IsNullOrWhiteSpace(value)) return;
                 text = value;
             }
         }
diff --git a/Sources/Stim.Model/User.cs b/Sources/Stim.Model/User.cs
index 7d1ddc4..28c6f02 100644
--- a/Sources/Stim.Model/User.cs
+++ b/Sources/Stim.Model/User.cs
@@ -9,7 +9,7 @@ namespace Model
             get { return username; }
             private set
             {
-                if (value == null || value == "") return;
+                if (string.IsNullOrWhiteSpace(value)) return;
                 username = value;
             }
         }
@@ -20,11 +20,11 @@ namespace Model
             get { return biographie;} 
             private set
             {
-                if (value == null || value == "") return;
+                if (string.IsNullOrWhiteSpace(value)) return;
                 biographie = value;
             }
         }
-        private string? biographie;
+        private string biographie;
 
         public string Email
         {
@@ -32,7 +32,7 @@ namespace Model
             private set
             {
                 Regex rg_email = new Regex("^[\\w-\\.]+@([\\w-]+\\.)+[\\w-]{2,4}$");
-                if (value != null && rg_email.IsMatch(value))
+                if (string.IsNullOrWhiteSpace(value) && rg_email.IsMatch(value))
                     email = value;
                 return;
             }
@@ -45,7 +45,7 @@ namespace Model
             private set
             {
                 Regex rg = new Regex("^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[#?!@$%^&*-]).{8,32}$");
-                if (value==null || !rg.IsMatch(value)) return;
+                if (string.IsNullOrWhiteSpace(value) || !rg.IsMatch(value)) return;
                 password = value;
             }
         }