diff --git a/sqlite_utils/cli.py b/sqlite_utils/cli.py
index e2862d5..4cb080f 100644
--- a/sqlite_utils/cli.py
+++ b/sqlite_utils/cli.py
@@ -686,7 +686,7 @@ def insert_upsert_implementation(
         raise click.ClickException("--encoding must be used with --csv or --tsv")
     encoding = encoding or "utf-8"
     buffered = io.BufferedReader(json_file, buffer_size=4096)
-    decoded = io.TextIOWrapper(buffered, encoding=encoding, line_buffering=True)
+    decoded = io.TextIOWrapper(buffered, encoding=encoding)
     if pk and len(pk) == 1:
         pk = pk[0]
     if csv or tsv: