diff --git a/crates/jstz_crypto/src/hash.rs b/crates/jstz_crypto/src/hash.rs
index 92e8fa707..5c48952ba 100644
--- a/crates/jstz_crypto/src/hash.rs
+++ b/crates/jstz_crypto/src/hash.rs
@@ -7,6 +7,7 @@ use boa_gc::{empty_trace, Finalize, Trace};
 use derive_more::{Display, Error};
 use hex::FromHexError;
 use serde::{Deserialize, Serialize};
+use utoipa::ToSchema;
 
 #[derive(
     Debug,
@@ -20,6 +21,7 @@ use serde::{Deserialize, Serialize};
     Deserialize,
     Default,
     Finalize,
+    ToSchema,
 )]
 pub struct Blake2b([u8; 32]);
 
diff --git a/crates/jstz_node/openapi.json b/crates/jstz_node/openapi.json
index e53c917f8..7a9b367fa 100644
--- a/crates/jstz_node/openapi.json
+++ b/crates/jstz_node/openapi.json
@@ -419,6 +419,14 @@
   },
   "components": {
     "schemas": {
+      "Blake2b": {
+        "type": "array",
+        "items": {
+          "type": "integer",
+          "format": "int32",
+          "minimum": 0
+        }
+      },
       "Content": {
         "oneOf": [
           {
@@ -666,7 +674,7 @@
         ],
         "properties": {
           "hash": {
-            "type": "string"
+            "$ref": "#/components/schemas/Blake2b"
           },
           "inner": {
             "$ref": "#/components/schemas/ReceiptResult"
diff --git a/crates/jstz_proto/src/receipt.rs b/crates/jstz_proto/src/receipt.rs
index dbc459388..202da939f 100644
--- a/crates/jstz_proto/src/receipt.rs
+++ b/crates/jstz_proto/src/receipt.rs
@@ -28,7 +28,6 @@ impl From<Result<ReceiptContent>> for ReceiptResult {
 
 #[derive(Debug, Clone, Serialize, Deserialize, ToSchema)]
 pub struct Receipt {
-    #[schema(value_type = String)]
     hash: OperationHash,
     pub inner: ReceiptResult,
 }