diff --git a/grzyClothTool/Views/BuildWindow.xaml b/grzyClothTool/Views/BuildWindow.xaml
index cdf48fd..ad5c5c5 100644
--- a/grzyClothTool/Views/BuildWindow.xaml
+++ b/grzyClothTool/Views/BuildWindow.xaml
@@ -38,12 +38,12 @@
             </GroupBox>
             
             <c:ModernLabelTextBox 
-            x:Name="name"
-            Label="Project name"
-            Margin="15,15,15,0"
-            VerticalAlignment="Top"
-            HorizontalAlignment="Stretch"
-            Text="{Binding ProjectName}" />
+                x:Name="name"
+                Label="Project name"
+                Margin="15,15,15,0"
+                VerticalAlignment="Top"
+                HorizontalAlignment="Stretch"
+                Text="{Binding ProjectName}" />
 
             <c:ModernLabelTextBox 
                 x:Name="output"
diff --git a/grzyClothTool/Views/BuildWindow.xaml.cs b/grzyClothTool/Views/BuildWindow.xaml.cs
index 1615c56..0104d92 100644
--- a/grzyClothTool/Views/BuildWindow.xaml.cs
+++ b/grzyClothTool/Views/BuildWindow.xaml.cs
@@ -4,6 +4,7 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
+using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Input;
@@ -40,6 +41,13 @@ private void Window_MouseDown(object sender, MouseButtonEventArgs e)
 
         private async void build_MyBtnClickEvent(object sender, RoutedEventArgs e)
         {
+            var error = ValidateProjectName();
+            if (error != null)
+            {
+                MessageBox.Show(error);
+                return;
+            }
+
             if (ProjectName == null || BuildPath == null)
             {
                 MessageBox.Show("Please fill in all fields");
@@ -121,5 +129,30 @@ private void RadioButton_ChangedEvent(object sender, RoutedEventArgs e)
                 };
             }
         }
+
+        private string ValidateProjectName()
+        {
+            string result = null;
+
+            if (string.IsNullOrEmpty(ProjectName))
+            {
+                result = "Project name cannot be empty";
+            }
+            else if (ProjectName.Length < 3)
+            {
+                result = "Project name must be at least 3 characters long";
+            }
+            else if (ProjectName.Length > 50)
+            {
+                result = "Project name cannot be longer than 50 characters";
+            }
+            else if (!Regex.IsMatch(ProjectName, @"^[a-z0-9_]+$"))
+            {
+                result = "Project name can only contain lowercase letters, numbers, and underscores";
+
+            }
+
+            return result;
+        }
     }
 }