Index: src/wp-admin/js/theme.js
===================================================================
--- src/wp-admin/js/theme.js	(revision 36122)
+++ src/wp-admin/js/theme.js	(working copy)
@@ -716,7 +716,17 @@
 
 	// Confirmation dialog for deleting a theme
 	deleteTheme: function() {
-		return confirm( themes.data.settings.confirmDelete );
+		event.preventDefault();
+
+		$( '#delete-theme-dialog' ).removeClass( 'hidden' );
+		$( '#delete-theme-dialog-message' ).html( '<h3>' + themes.data.settings.confirmDelete + '</h3>' );
+
+		$( '#delete-theme-dialog-cancel' ).on( 'click', function() {
+			$( '#delete-theme-dialog' ).addClass( 'hidden' );
+		});
+
+		$( '#delete-theme-dialog-confirm' ).attr( 'href', $( '.delete-theme' ).attr( 'href' ) );
+
 	},
 
 	nextTheme: function() {
Index: src/wp-admin/themes.php
===================================================================
--- src/wp-admin/themes.php	(revision 36122)
+++ src/wp-admin/themes.php	(working copy)
@@ -461,5 +461,18 @@
 		</div>
 	</div>
 </script>
-
+<div id="delete-theme-dialog" class="notification-dialog-wrap hidden">
+	<div class="notification-dialog-background"></div>
+	<div class="notification-dialog" style="padding:25px;">
+		<p>
+			<div id="delete-theme-dialog-message">
+					
+			</div>
+		</p>
+		<p>
+			<a id="delete-theme-dialog-cancel" class="button button-secondary">Cancel</a>
+			<a id="delete-theme-dialog-confirm" class="button button-primary">Ok</a>
+		</p>
+	</div>
+</div>
 <?php require( ABSPATH . 'wp-admin/admin-footer.php' );