diff --git a/CHANGES b/CHANGES
index 91133c39..99717d70 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4,6 +4,9 @@ PyVISA-py Changelog
 0.7.3 (unreleased)
 ------------------
 
+- ignore network interface card with no subnet mask when discovering TCPIP
+  resources PR #478
+- add VICP INSTR to the supported interface for TCPIP keep alive attr PR #477
 - add read_stb method for TCPIP HiSLIP client PR #429
 - fix usbtmc implementation to respect section 3.3 of the spec PR #449
   Read now reads from usb until a "short packet" or if all data (`transfer_size`) PR #465
diff --git a/pyvisa_py/tcpip.py b/pyvisa_py/tcpip.py
index 3c6f4a88..0b0d9f2a 100644
--- a/pyvisa_py/tcpip.py
+++ b/pyvisa_py/tcpip.py
@@ -419,7 +419,7 @@ def list_resources() -> List[str]:
             # Get broadcast address for each interface
             for interface, snics in psutil.net_if_addrs().items():
                 for snic in snics:
-                    if snic.family is socket.AF_INET:
+                    if snic.family is socket.AF_INET and snic.netmask is not None:
                         addr = snic.address
                         mask = snic.netmask
                         network = ipaddress.IPv4Network(addr + "/" + mask, strict=False)