diff --git a/src/display/editor/editor.js b/src/display/editor/editor.js
index 3c58ba1f3..1d282ebe9 100644
--- a/src/display/editor/editor.js
+++ b/src/display/editor/editor.js
@@ -1213,9 +1213,18 @@ class AnnotationEditor {
 
   addComment(serialized) {
     if (this.hasEditedComment) {
+      const DEFAULT_POPUP_WIDTH = 180;
+      const DEFAULT_POPUP_HEIGHT = 100;
+      const [, , , trY] = serialized.rect;
+      const [pageWidth] = this.pageDimensions;
+      const [pageX] = this.pageTranslation;
+      const blX = pageX + pageWidth + 1;
+      const blY = trY - DEFAULT_POPUP_HEIGHT;
+      const trX = blX + DEFAULT_POPUP_WIDTH;
       serialized.popup = {
         contents: this.comment.text,
         deleted: this.comment.deleted,
+        rect: [blX, blY, trX, trY],
       };
     }
   }
diff --git a/test/unit/annotation_spec.js b/test/unit/annotation_spec.js
index 46617e5ba..ca728571b 100644
--- a/test/unit/annotation_spec.js
+++ b/test/unit/annotation_spec.js
@@ -4995,6 +4995,7 @@ describe("annotation", function () {
             rotation: 90,
             popup: {
               contents: "Hello PDF.js World !",
+              rect: [1, 2, 3, 4],
             },
             id: "143R",
             ref: highlightRef,
@@ -5010,7 +5011,7 @@ describe("annotation", function () {
       const popup = data[0];
       expect(popup.data).toEqual(
         "1 0 obj\n" +
-          "<< /Type /Annot /Subtype /Popup /Open false /Parent 143 0 R>>\n" +
+          "<< /Type /Annot /Subtype /Popup /Open false /Rect [1 2 3 4] /Parent 143 0 R>>\n" +
           "endobj\n"
       );