diff --git a/marine/marine.py b/marine/marine.py
index 236fec0..6f7ef4d 100644
--- a/marine/marine.py
+++ b/marine/marine.py
@@ -50,7 +50,7 @@ class Marine:
 
     def __init__(self, epan_auto_reset_count: Optional[int] = None):
         if not os.getenv("WIRESHARK_DATA_DIR"):
-            os.putenv("WIRESHARK_DATA_DIR", str(MARINE_DATA_DIR))
+            os.environ["WIRESHARK_DATA_DIR"] = str(MARINE_DATA_DIR)
         try:
             cdll.LoadLibrary(MARINE_NAME)
         except Exception:
diff --git a/tests/marine/test_marine.py b/tests/marine/test_marine.py
index 1e5fd87..635fe78 100644
--- a/tests/marine/test_marine.py
+++ b/tests/marine/test_marine.py
@@ -1025,3 +1025,7 @@ def test_parse_fields_preserves_order(marine_instance: Marine, tcp_packet: bytes
         "udp.srcport": None,
         "tcp.srcport": "16424",
     }
+
+
+def test_filter_packet_larger_than_1514(marine_instance: Marine):
+    assert not marine_instance.filter(b"a" * 2500, display_filter="frame contains test")