diff --git a/src/Avalonia.Controls/ComboBox.cs b/src/Avalonia.Controls/ComboBox.cs
index f02df2e9c1..a0085c92ca 100644
--- a/src/Avalonia.Controls/ComboBox.cs
+++ b/src/Avalonia.Controls/ComboBox.cs
@@ -213,7 +213,12 @@ namespace Avalonia.Controls
                 IsDropDownOpen = false;
                 e.Handled = true;
             }
-            else if (IsDropDownOpen && e.Key == Key.Enter)
+            else if (!IsDropDownOpen && (e.Key == Key.Enter || e.Key == Key.Space))
+            {
+                IsDropDownOpen = true;
+                e.Handled = true;
+            }
+            else if (IsDropDownOpen && (e.Key == Key.Enter || e.Key == Key.Space))
             {
                 SelectFocusedItem();
                 IsDropDownOpen = false;