diff --git a/src/kmessagebox.cpp b/src/kmessagebox.cpp
--- a/src/kmessagebox.cpp
+++ b/src/kmessagebox.cpp
@@ -347,6 +347,16 @@
     }
 
     buttons->setParent(dialog);
+
+    // try to set the focus to a default button.
+    Q_FOREACH(QAbstractButton* button, buttons->buttons()) {
+        QPushButton* btn = dynamic_cast<QPushButton*>(button);
+
+        if (btn != nullptr && btn->isDefault()) {
+            btn->setFocus();
+        }
+    }
+
     topLayout->addWidget(buttons);
 
     if (!usingListWidget && !usingScrollArea && !usingSqueezedTextLabel && details.isEmpty()) {