diff --git a/lib/src/chain/async_tree.rs b/lib/src/chain/async_tree.rs
index 7e9b2cb5f4..2c97c76f07 100644
--- a/lib/src/chain/async_tree.rs
+++ b/lib/src/chain/async_tree.rs
@@ -788,7 +788,9 @@ where
             },
         );
 
-        self.input_best_block_index = Some(new_index);
+        if is_new_best {
+            self.input_best_block_index = Some(new_index);
+        }
 
         new_index
     }
diff --git a/wasm-node/CHANGELOG.md b/wasm-node/CHANGELOG.md
index 9b617d30bc..aee3a8d193 100644
--- a/wasm-node/CHANGELOG.md
+++ b/wasm-node/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+### Fixed
+
+- Fix potential panic in parachain syncing code. ([#1912](https://github.com/smol-dot/smoldot/pull/1912))
+
 ## 2.0.29 - 2024-06-17
 
 ### Fixed