diff --git a/lib/main.js b/lib/main.js
index c63018d..d211524 100644
--- a/lib/main.js
+++ b/lib/main.js
@@ -104,13 +104,18 @@
 					runAt: "document_start",
 					js: [{
 						code: `(function(){
-							const settings = require("./settings");
-							const logging = require("./logging");
-							if (settings.init(${JSON.stringify(data)})){
-								logging.message("Initialized settings by dynamic content script.");
+							if (typeof require !== "undefined"){
+								const settings = require("./settings");
+								const logging = require("./logging");
+								if (settings.init(${JSON.stringify(data)})){
+									logging.message("Initialized settings by dynamic content script.");
+								}
+								else {
+									logging.error("Dynamic content script was too late to provide settings.");
+								}
 							}
 							else {
-								logging.error("Dynamic content script was too late to provide settings.");
+								console.error("[CanvasBlocker] invalid content scripts: require not defined");
 							}
 						}())`
 					}]