diff --git a/install/install.php b/install/install.php
index ddb08ad..6fd0c8f 100644
--- a/install/install.php
+++ b/install/install.php
@@ -21,6 +21,13 @@
 	exit;
 }
 
+if(!isset($runtime_paths)){
+	echo ">>> ERROR:\n";
+	echo "variable runtime_paths is not set. Please edit/correct conf.php. See conf-sample.php for details\n";
+	exit;
+}
+
+
 if(!file_exists( "$path_website/data" )) {
 	// create the data directory
 	mkdir( "$path_website/data" );