diff --git a/src/hdmf_zarr/backend.py b/src/hdmf_zarr/backend.py
index eaad2f1c..8f73ebea 100644
--- a/src/hdmf_zarr/backend.py
+++ b/src/hdmf_zarr/backend.py
@@ -638,7 +638,7 @@ def write_attributes(self, **kwargs):
                     if isinstance(value, Builder):
                         refs = self._create_ref(value, export_source)
                     else:
-                        refs = self._create_ref(value.builder, export_source);
+                        refs = self._create_ref(value.builder, export_source)
                 tmp = {'zarr_dtype': type_str, 'value': refs}
                 obj.attrs[key] = tmp
             # Case 3: Scalar attributes