diff --git a/scripts/build.py b/scripts/build.py
index 7b83689..a6d6ba1 100644
--- a/scripts/build.py
+++ b/scripts/build.py
@@ -54,6 +54,11 @@ def upsert_vuln(db, vid, published=None, modified=None, state=None, summary=None
 
 
 def process_cve(db, obj):
+    if not isinstance(obj, dict):
+      raise ValueError(
+        f"Unexpected CVE JSON type: {type(obj).__name__}; "
+        f"sample={str(obj)[:300]}"
+    )
     m = obj.get('cveMetadata')
     if not isinstance(m,dict):
         return False