diff --git a/lexicons/so/sprk/feed/like.json b/lexicons/so/sprk/feed/like.json
index 8723637..c7a3d3a 100644
--- a/lexicons/so/sprk/feed/like.json
+++ b/lexicons/so/sprk/feed/like.json
@@ -4,7 +4,7 @@
   "defs": {
     "main": {
       "type": "record",
-      "description": "Record declaring a 'like' of a piece of subject content.",
+      "description": "Record declaring a 'like' of a piece of subject content. Duplicate likes from the same author to the same subject will be ignored by the AppView.",
       "key": "tid",
       "record": {
         "type": "object",
diff --git a/services/ingester/src/db/models.ts b/services/ingester/src/db/models.ts
index 4b84cdc..8495512 100644
--- a/services/ingester/src/db/models.ts
+++ b/services/ingester/src/db/models.ts
@@ -22,6 +22,9 @@ export const likeSchema = new Schema<LikeDocument>({
   cid: { type: String, required: true },
 })
 
+// Add compound index to prevent duplicate likes
+likeSchema.index({ authorDid: 1, subject: 1 }, { unique: true })
+
 export interface LookDocument extends Document {
   uri: string
   subject: string