diff --git a/pyserini/search/lucene/_impact_searcher.py b/pyserini/search/lucene/_impact_searcher.py
index 657c699fa..4782c61b5 100644
--- a/pyserini/search/lucene/_impact_searcher.py
+++ b/pyserini/search/lucene/_impact_searcher.py
@@ -131,8 +131,6 @@ def search(self, q: str, k: int = 10, fields=dict()) -> List[JImpactSearcherResu
             Query string.
         k : int
             Number of hits to return.
-        min_idf : int
-            Minimum idf for query tokens
         fields : dict
             Optional map of fields to search with associated boosts.
 
@@ -176,8 +174,6 @@ def batch_search(self, queries: List[str], qids: List[str],
             Number of hits to return.
         threads : int
             Maximum number of threads to use.
-        min_idf : int
-            Minimum idf for query tokens
         fields : dict
             Optional map of fields to search with associated boosts.