diff --git a/netstack/src/scheme/tcp.rs b/netstack/src/scheme/tcp.rs
index 28da52a70a..c63e32a9a4 100644
--- a/netstack/src/scheme/tcp.rs
+++ b/netstack/src/scheme/tcp.rs
@@ -54,7 +54,11 @@ impl<'a> SchemeSocket for TcpSocket<'a> {
         metadata: &[u64],
         _ctx: &CallerCtx,
     ) -> SyscallResult<usize> {
-        match SocketCall::from(metadata[0]) {
+        let verb = match SocketCall::try_from_raw(metadata[0] as usize) {
+            Some(v) => v,
+            None => return Err(SyscallError::new(syscall::EINVAL)),
+        };
+        match verb {
             SocketCall::SendMsg => {
                 let flags = metadata[1] as u16;
                 // smoltcp's TCP socket has no MSG_NOSIGNAL awareness: a