diff --git a/ariba/summary_cluster_variant.py b/ariba/summary_cluster_variant.py
index 51e00d95..fa9a8670 100644
--- a/ariba/summary_cluster_variant.py
+++ b/ariba/summary_cluster_variant.py
@@ -33,7 +33,7 @@ def _has_nonsynonymous(cls, data_dict):
 
     @classmethod
     def _get_het_percent(cls, data_dict):
-        if data_dict['gene'] == '1' or data_dict['ref_ctg_effect'] != 'SNP' or data_dict['smtls_alt_nt'] == '.' or ';' in data_dict['smtls_alt_nt']:
+        if data_dict['gene'] == '1' or data_dict['ref_ctg_effect'] != 'SNP' or data_dict['smtls_alt_nt'] == '.' or ';' in data_dict['smtls_alt_nt'] or data_dict['smtls_alt_depth'] == 'ND':
             return None
         else:
             nucleotides = [data_dict['ctg_nt']] + data_dict['smtls_alt_nt'].split(',')
diff --git a/setup.py b/setup.py
index 5a7e806e..4e8a8372 100644
--- a/setup.py
+++ b/setup.py
@@ -51,7 +51,7 @@
 setup(
     ext_modules=[minimap_mod, fermilite_mod],
     name='ariba',
-    version='2.2.2',
+    version='2.2.3',
     description='ARIBA: Antibiotic Resistance Identification By Assembly',
     packages = find_packages(),
     package_data={'ariba': ['test_run_data/*']},