diff --git a/Base.lproj/SplashWindow.xib b/Base.lproj/SplashWindow.xib
index dc2a318..39a70a6 100644
--- a/Base.lproj/SplashWindow.xib
+++ b/Base.lproj/SplashWindow.xib
@@ -14,7 +14,7 @@
         </customObject>
         <customObject id="-1" userLabel="First Responder" customClass="FirstResponder"/>
         <customObject id="-3" userLabel="Application" customClass="NSObject"/>
-        <window title="Welcome to Add Folder Icons" allowsToolTipsWhenApplicationIsInactive="NO" autorecalculatesKeyViewLoop="NO" visibleAtLaunch="NO" animationBehavior="default" id="1">
+        <window title="Welcome to Add Folder Icons" allowsToolTipsWhenApplicationIsInactive="NO" autorecalculatesKeyViewLoop="NO" releasedWhenClosed="NO" visibleAtLaunch="NO" animationBehavior="default" id="1">
             <windowStyleMask key="styleMask" titled="YES"/>
             <windowPositionMask key="initialPositionMask" leftStrut="YES" rightStrut="YES" topStrut="YES" bottomStrut="YES"/>
             <rect key="contentRect" x="196" y="240" width="800" height="500"/>
diff --git a/SplashWindowController.m b/SplashWindowController.m
index 61684c7..7e260d4 100644
--- a/SplashWindowController.m
+++ b/SplashWindowController.m
@@ -49,6 +49,20 @@ - ( void ) windowDidLoad
 {
     [ super windowDidLoad ];
 
+    /* The main window's NIB sets "released when closed" to NO, but the splash
+     * window's NIB does not, so the splash window defaults to releasing itself
+     * on close. On modern macOS that is fatal: when the splash window is the
+     * key window and is closed, it is deallocated, yet AppKit's automatic
+     * focus-ring machinery still references it when first-responder status
+     * moves back to the main window. The result is a use-after-free crash in
+     * +[_NSAutomaticFocusRing _clearOldFocusRing] -> -[NSWindow
+     * _setNeedsDisplayInRegion:]. This controller owns the window for the
+     * lifetime of the application, so keep it alive on close, matching the
+     * behaviour already configured for the main window.
+     */
+
+    [ [ self window ] setReleasedWhenClosed: NO ];
+
     [ [ self window ] center ];
     [ [ self window ] makeKeyAndOrderFront: nil ];
 }
@@ -65,7 +79,13 @@ - ( void ) windowDidLoad
 - ( IBAction ) closeWindow: ( NSButton * ) sender
 {
     ( void ) sender;
-    [ self close ]; 
+
+    /* Resign first responder before the window goes away so that AppKit tears
+     * down any focus ring while the window is still a valid object.
+     */
+
+    [ [ self window ] makeFirstResponder: nil ];
+    [ self close ];
 }
 
 @end