diff --git a/upb/message/accessors.c b/upb/message/accessors.c
index 43a79b9a9a..76b55041ba 100644
--- a/upb/message/accessors.c
+++ b/upb/message/accessors.c
@@ -147,7 +147,7 @@ upb_GetExtensionAsBytes_Status upb_MiniTable_GetExtensionAsBytes(
   return kUpb_GetExtensionAsBytes_Ok;
 }
 
-upb_FindUnknownRet upb_FindUnknownRet_ParseError() {
+static upb_FindUnknownRet upb_FindUnknownRet_ParseError() {
   return (upb_FindUnknownRet){.status = kUpb_FindUnknown_ParseError};
 }