diff --git a/src/stream/src/executor/hash_join.rs b/src/stream/src/executor/hash_join.rs
index 3fcf0032e4975..427b036fe7fe1 100644
--- a/src/stream/src/executor/hash_join.rs
+++ b/src/stream/src/executor/hash_join.rs
@@ -830,6 +830,8 @@ impl<K: HashKey, S: StateStore, const T: JoinTypePrimitive> HashJoinExecutor<K,
             if let Some(rows) = &matched_rows {
                 join_matched_join_keys.observe(rows.len() as _);
                 if rows.len() > 10000 {
+                    let join_key_data_types = side_update.ht.join_key_data_types();
+                    let key = key.deserialize(join_key_data_types)?;
                     tracing::debug!(target: "hash_join_amplification",
                         matched_rows_len = rows.len(),
                         update_table_id = side_update.ht.table_id(),
diff --git a/src/stream/src/executor/join/hash_join.rs b/src/stream/src/executor/join/hash_join.rs
index 8805ea3cc3120..0c6a12b1e68f5 100644
--- a/src/stream/src/executor/join/hash_join.rs
+++ b/src/stream/src/executor/join/hash_join.rs
@@ -626,6 +626,10 @@ impl<K: HashKey, S: StateStore> JoinHashMap<K, S> {
     pub fn table_id(&self) -> u32 {
         self.state.table.table_id()
     }
+
+    pub fn join_key_data_types(&self) -> &[DataType] {
+        &self.join_key_data_types
+    }
 }
 
 use risingwave_common_estimate_size::KvSize;