diff --git a/kgx/source/obograph_source.py b/kgx/source/obograph_source.py
index b5a7d5f4..58ae1d95 100644
--- a/kgx/source/obograph_source.py
+++ b/kgx/source/obograph_source.py
@@ -333,7 +333,7 @@ def parse_meta(self, node: str, meta: Dict) -> Dict:
 
         if "synonyms" in meta:
             # parse 'synonyms' as 'synonym'
-            synonyms = [s["val"] for s in meta["synonyms"]]
+            synonyms = [s["val"] for s in meta["synonyms"] if "val" in s]
             properties["synonym"] = synonyms
 
         if "xrefs" in meta: