diff --git a/ext/fg/js/popup.js b/ext/fg/js/popup.js
index 396a5be9..a9fde7b6 100644
--- a/ext/fg/js/popup.js
+++ b/ext/fg/js/popup.js
@@ -79,6 +79,10 @@ class Popup {
         });
     }
 
+    isInitialized() {
+        return this.options !== null;
+    }
+
     async setOptions(options) {
         this.options = options;
     }
@@ -212,6 +216,7 @@ class Popup {
     }
 
     async showOrphaned(elementRect, writingMode, options) {
+        if (!this.isInitialized()) { return; }
         await this.show(elementRect, writingMode, options);
         this.invokeApi('orphaned');
     }
@@ -275,11 +280,13 @@ class Popup {
     }
 
     async termsShow(elementRect, writingMode, definitions, options, context) {
+        if (!this.isInitialized()) { return; }
         await this.show(elementRect, writingMode, options);
         this.invokeApi('termsShow', {definitions, options, context});
     }
 
     async kanjiShow(elementRect, writingMode, definitions, options, context) {
+        if (!this.isInitialized()) { return; }
         await this.show(elementRect, writingMode, options);
         this.invokeApi('kanjiShow', {definitions, options, context});
     }
diff --git a/ext/mixed/js/display.js b/ext/mixed/js/display.js
index 0d7be355..d5d055e0 100644
--- a/ext/mixed/js/display.js
+++ b/ext/mixed/js/display.js
@@ -187,6 +187,10 @@ class Display {
         throw new Error('Override me');
     }
 
+    isInitialized() {
+        return this.options !== null;
+    }
+
     async initialize(options=null) {
         await this.updateOptions(options);
         chrome.runtime.onMessage.addListener(this.onRuntimeMessage.bind(this));
@@ -236,6 +240,8 @@ class Display {
     }
 
     async termsShow(definitions, options, context) {
+        if (!this.isInitialized()) { return; }
+
         try {
             this.setEventListenersActive(false);
 
@@ -287,6 +293,8 @@ class Display {
     }
 
     async kanjiShow(definitions, options, context) {
+        if (!this.isInitialized()) { return; }
+
         try {
             this.setEventListenersActive(false);