diff --git a/index.js b/index.js
index 621a28e..c5c4d69 100644
--- a/index.js
+++ b/index.js
@@ -332,7 +332,7 @@ function runWarc2Zim(params, checkOnly = true) {
           break;
 
         case "object":
-          zimOptsStr += params[key].join(` --${key} `);
+          zimOptsStr += params[key].map(x => `"${x}"`).join(` --${key} `) + " ";
           break;
       }
     }