diff --git a/vulnerabilitylookup/feeders/gsd.py b/vulnerabilitylookup/feeders/gsd.py
index 9bd28086..2f45992b 100644
--- a/vulnerabilitylookup/feeders/gsd.py
+++ b/vulnerabilitylookup/feeders/gsd.py
@@ -93,9 +93,19 @@ def gsd_update(self) -> bool:
                         last_modified = datetime.fromisoformat(vuln['gsd']['osvSchema']['modified'])
                 if not last_modified and 'namespaces' in vuln:
                     if 'nvd.nist.gov' in vuln['namespaces']:
-                        last_modified = datetime.fromisoformat(vuln['namespaces']['nvd.nist.gov']['lastModifiedDate'])
+                        try:
+                            last_modified = datetime.fromisoformat(vuln['namespaces']['nvd.nist.gov']['lastModifiedDate'])
+                        except ValueError as e:
+                            # nothing important, just a broken date
+                            self.logger.warning(f'Unable to get modified date: {e}')
+                            needs_lastmodified_from_git = True
                     elif 'gitlab.com' in vuln['namespaces']:
-                        last_modified = datetime.fromisoformat(vuln['namespaces']['gitlab.com']['advisories'][0]['date'])
+                        try:
+                            last_modified = datetime.fromisoformat(vuln['namespaces']['gitlab.com']['advisories'][0]['date'])
+                        except ValueError as e:
+                            # nothing important, just a broken date
+                            self.logger.warning(f'Unable to get modified date: {e}')
+                            needs_lastmodified_from_git = True
                     else:
                         if 'cve.org' in vuln['namespaces'] and vuln['namespaces']['cve.org']['CVE_data_meta']['STATE'] == 'RESERVED':
                             # reserved ID