diff --git a/src/Avalonia.Controls/StackPanel.cs b/src/Avalonia.Controls/StackPanel.cs
index 0e12fb3283..a6fe35d668 100644
--- a/src/Avalonia.Controls/StackPanel.cs
+++ b/src/Avalonia.Controls/StackPanel.cs
@@ -170,6 +170,15 @@ namespace Avalonia.Controls
                 }
             }
 
+            if (Orientation == Orientation.Vertical)
+            {
+                measuredHeight -= gap;
+            }
+            else
+            {
+                measuredWidth -= gap;
+            }
+
             return new Size(measuredWidth, measuredHeight);
         }