diff --git a/proto/icon/v1.proto b/proto/icon/v1.proto
index 364595e..6014244 100644
--- a/proto/icon/v1.proto
+++ b/proto/icon/v1.proto
@@ -31,9 +31,14 @@ message Icon_1 {
       png = 1;
     }
 
+    message BlobVersionId {
+      bytes coreDiscoveryKey = 1;
+      int32 index = 2;
+    }
+
     Size size = 1 [(required) = true];
     PixelDensity pixelDensity = 2 [(required) = true];
-    bytes blobVersionId = 3 [(required) = true];
+    BlobVersionId blobVersionId = 3 [(required) = true];
     MimeType mimeType = 4 [(required) = true];
   }
 
diff --git a/schema/icon/v1.json b/schema/icon/v1.json
index 1fde761..28c1cd6 100644
--- a/schema/icon/v1.json
+++ b/schema/icon/v1.json
@@ -27,6 +27,7 @@
             "enum": [1,2,3]
           },
           "blobVersionId": {
+      "description": "Version id of the icon blob. Each id is id (hex-encoded 32 byte buffer) and index number, separated by '/'",
             "type": "string"
           },
           "mimeType": {
diff --git a/src/lib/decode-conversions.ts b/src/lib/decode-conversions.ts
index b7b0e1c..11eca04 100644
--- a/src/lib/decode-conversions.ts
+++ b/src/lib/decode-conversions.ts
@@ -206,8 +206,11 @@ export const convertIcon: ConvertFunction<'icon'> = (message, versionObj) => {
 
 function convertIconVariant(variant: Icon_1_IconVariant) {
   const { blobVersionId, mimeType, size, pixelDensity } = variant
+  if (!blobVersionId) {
+    throw new Error('Missing required property `blobVersionId`')
+  }
   return {
-    blobVersionId: blobVersionId.toString('hex'),
+    blobVersionId: getVersionId(blobVersionId),
     mimeType: convertIconMimeType(mimeType),
     size: size === 'UNRECOGNIZED' ? 'medium' : size,
     pixelDensity: convertIconPixelDensity(pixelDensity),
diff --git a/src/lib/encode-conversions.ts b/src/lib/encode-conversions.ts
index 95594ac..447e16a 100644
--- a/src/lib/encode-conversions.ts
+++ b/src/lib/encode-conversions.ts
@@ -147,7 +147,7 @@ function convertIconVariants(variants: Icon['variants']): Icon_1_IconVariant[] {
   return variants.map((variant) => {
     const { blobVersionId, mimeType, size, pixelDensity } = variant
     return {
-      blobVersionId: Buffer.from(blobVersionId, 'hex'),
+      blobVersionId: parseVersionId(blobVersionId),
       mimeType: convertIconMimeType(mimeType),
       size,
       pixelDensity: convertIconPixelDensity(pixelDensity),
diff --git a/test/fixtures/good-docs-completed.js b/test/fixtures/good-docs-completed.js
index 3de85c2..45a8def 100644
--- a/test/fixtures/good-docs-completed.js
+++ b/test/fixtures/good-docs-completed.js
@@ -215,13 +215,13 @@ export const goodDocsCompleted = [
         {
           size: 'small',
           pixelDensity: 1,
-          blobVersionId: randomBytes(32).toString('hex'),
+          blobVersionId: randomBytes(32).toString('hex') + '/0',
           mimeType: 'image/png',
         },
         {
           size: 'large',
           pixelDensity: 3,
-          blobVersionId: randomBytes(32).toString('hex'),
+          blobVersionId: randomBytes(32).toString('hex') + '/0',
           mimeType: 'image/svg+xml',
         },
       ],
diff --git a/test/fixtures/good-docs-minimal.js b/test/fixtures/good-docs-minimal.js
index 748de0e..3ce92ac 100644
--- a/test/fixtures/good-docs-minimal.js
+++ b/test/fixtures/good-docs-minimal.js
@@ -148,7 +148,7 @@ export const goodDocsMinimal = [
         {
           size: 'small',
           pixelDensity: 1,
-          blobVersionId: randomBytes(32).toString('hex'),
+          blobVersionId: randomBytes(32).toString('hex') + '/0',
           mimeType: 'image/png',
         },
       ],