diff --git a/src/components/thumbnail.ts b/src/components/thumbnail.ts
index 6c2b0172..913a8005 100644
--- a/src/components/thumbnail.ts
+++ b/src/components/thumbnail.ts
@@ -57,6 +57,10 @@ export class FrigateCardThumbnailFeatureEvent extends LitElement {
     return new Promise((resolve, reject) => {
       //eslint-disable-next-line @typescript-eslint/no-non-null-assertion
       this.hass!.fetchWithAuth(thumbnail)
+      // Since we are fetching with an authorization header, we cannot just put the
+      // URL directly into the document; we need to embed the image. We could do this
+      // using blob URLs, but then we would need to keep track of them in order to
+      // release them properly. Instead, we embed the thumbnail using base64.
         .then((response) => response.blob())
         .then((blob) => {
           const reader = new FileReader();