diff --git a/src/macos/SerialPortMACOS.cxx b/src/macos/SerialPortMACOS.cxx
index 86490f7a6..8398123e5 100644
--- a/src/macos/SerialPortMACOS.cxx
+++ b/src/macos/SerialPortMACOS.cxx
@@ -101,14 +101,14 @@ StringList SerialPortMACOS::portNames()
 
   // Check if port is valid; for now that means if it can be opened
   // Eventually we may extend this to do more intensive checks
-  auto isPortValid = [](const string& port) {
-    int handle = open(port.c_str(), O_RDWR | O_NOCTTY | O_NONBLOCK);
+  const auto isPortValid = [](const string& port) {
+    const int handle = open(port.c_str(), O_RDWR | O_NOCTTY | O_NONBLOCK);
     if(handle > 0)  close(handle);
     return handle > 0;
   };
 
   // Get all possible devices in the '/dev' directory
-  FilesystemNode::NameFilter filter = [](const FilesystemNode& node) {
+  const FilesystemNode::NameFilter filter = [](const FilesystemNode& node) {
     return BSPF::startsWithIgnoreCase(node.getPath(), "/dev/cu.usb");
   };
   FSList portList;