diff --git a/src/DotTiled/Properties/BoolProperty.cs b/src/DotTiled/Properties/BoolProperty.cs
index 0597e60..5e1d39b 100644
--- a/src/DotTiled/Properties/BoolProperty.cs
+++ b/src/DotTiled/Properties/BoolProperty.cs
@@ -17,7 +17,7 @@ public class BoolProperty : IProperty<bool>
   public required bool Value { get; set; }
 
   /// <inheritdoc/>
-  public string ValueString => Value.ToString();
+  public string ValueString => Value ? "true" : "false"; //Tiled outputs lowercase
 
   /// <inheritdoc/>
   public IProperty Clone() => new BoolProperty