--- a/below/ethtool/src/reader.rs
+++ b/below/ethtool/src/reader.rs
@@ -33,7 +33,7 @@ fn ioctl(
         ifr_ifru: libc::__c_anonymous_ifr_ifru { ifru_data: data },
     };
 
-    let exit_code = unsafe { libc::ioctl(fd.as_raw_fd(), nix::libc::SIOCETHTOOL, &ifr) };
+    let exit_code = unsafe { libc::ioctl(fd.as_raw_fd(), nix::libc::SIOCETHTOOL.try_into().unwrap(), &ifr) };
     if exit_code != 0 {
         return Err(Errno::from_i32(exit_code));
     }