diff --git a/doc/lua-filters.md b/doc/lua-filters.md
index efaeb6343..4ab1ef435 100644
--- a/doc/lua-filters.md
+++ b/doc/lua-filters.md
@@ -3918,7 +3918,7 @@ Usage:
 
 `run_json_filter (doc, filter[, args])`
 
-Filter the given doc by passing it through the a JSON filter.
+Filter the given doc by passing it through a JSON filter.
 
 Parameters: