diff --git a/netstack/src/scheme/socket.rs b/netstack/src/scheme/socket.rs
index e7d7c46421..213736df58 100644
--- a/netstack/src/scheme/socket.rs
+++ b/netstack/src/scheme/socket.rs
@@ -264,6 +264,7 @@ where
 fn get_sock_opt(
         &self,
         _file: &SchemeFile<Self>,
+        _level: usize,
         _name: usize,
         _buf: &mut [u8],
     ) -> SyscallResult<usize> {
@@ -273,6 +274,7 @@ fn get_sock_opt(
     fn set_sock_opt(
         &mut self,
         _file: &SchemeFile<Self>,
+        _level: usize,
         _name: usize,
         _buf: &[u8],
     ) -> SyscallResult<usize> {
@@ -475,10 +477,17 @@ where
                     Handle::File(file) => {
                         let mut socket_set = self.socket_set.borrow_mut();
                         let socket = socket_set.get_mut::<SocketT>(file.socket_handle());
+                        // Wire format: [SocketCall::SetSockOpt, level, option]
+                        // level is SOL_SOCKET (1), IPPROTO_TCP (6), IPPROTO_IP (0),
+                        // etc. Without level, option 4 reads as IP_TOS at
+                        // IPPROTO_IP when caller asked for TCP_KEEPIDLE at
+                        // SOL_SOCKET. See NETWORKING-AND-DRIVERS-CODE-ASSESSMENT
+                        // §3.4 (Finding 1.7: option collision).
                         SocketT::set_sock_opt(
                             socket,
                             file,
-                            metadata[1] as usize,
+                            metadata[1] as usize,  // level
+                            metadata[2] as usize,  // option
                             payload,
                         )
                     }
@@ -492,7 +501,13 @@ where
                     Handle::File(ref mut file) => {
                         let mut socket_set = self.socket_set.borrow_mut();
                         let socket = socket_set.get_mut::<SocketT>(file.socket_handle());
-                        SocketT::get_sock_opt(socket, file, metadata[1] as usize, payload)
+                        SocketT::get_sock_opt(
+                            socket,
+                            file,
+                            metadata[1] as usize,  // level
+                            metadata[2] as usize,  // option
+                            payload,
+                        )
                     }
                     Handle::Null(_) => {
                         // TODO
diff --git a/netstack/src/scheme/tcp.rs b/netstack/src/scheme/tcp.rs
index 1430a92a8b..cf4ed09bb5 100644
--- a/netstack/src/scheme/tcp.rs
+++ b/netstack/src/scheme/tcp.rs
@@ -427,6 +427,7 @@ impl<'a> SchemeSocket for TcpSocket<'a> {
     fn get_sock_opt(
         &self,
         _file: &SchemeFile<Self>,
+        _level: usize,
         name: usize,
         buf: &mut [u8],
     ) -> SyscallResult<usize> {
@@ -558,6 +559,7 @@ unsafe {
     fn set_sock_opt(
         &mut self,
         _file: &SchemeFile<Self>,
+        _level: usize,
         name: usize,
         buf: &[u8],
     ) -> SyscallResult<usize> {
diff --git a/netstack/src/scheme/udp.rs b/netstack/src/scheme/udp.rs
index 77893fc4fe..ed31957b9e 100644
--- a/netstack/src/scheme/udp.rs
+++ b/netstack/src/scheme/udp.rs
@@ -479,6 +479,7 @@ impl<'a> SchemeSocket for UdpSocket<'a> {
     fn get_sock_opt(
         &self,
         _file: &SchemeFile<Self>,
+        _level: usize,
         name: usize,
         buf: &mut [u8],
     ) -> SyscallResult<usize> {
@@ -516,6 +517,7 @@ impl<'a> SchemeSocket for UdpSocket<'a> {
     fn set_sock_opt(
         &mut self,
         _file: &SchemeFile<Self>,
+        _level: usize,
         name: usize,
         buf: &[u8],
     ) -> SyscallResult<usize> {