diff --git a/src/header/netdb/mod.rs b/src/header/netdb/mod.rs
index 366816135d..9c0804a8cc 100644
--- a/src/header/netdb/mod.rs
+++ b/src/header/netdb/mod.rs
@@ -421,9 +421,36 @@ pub unsafe extern "C" fn gethostbyname(name: *const c_char) -> *mut hostent {
     (&raw mut HOST_ENTRY).cast::<hostent>()
 }
 
-/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/endnetent.html>.
+/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/getnetbyaddr.html>.
+#[unsafe(no_mangle)]
 pub unsafe extern "C" fn getnetbyaddr(net: u32, net_type: c_int) -> *mut netent {
-    unimplemented!();
+    let mut n: *mut netent;
+    if net_type != AF_INET && net_type != AF_UNSPEC && net_type != AF_INET6 {
+        platform::ERRNO.set(ENOENT);
+        return ptr::null_mut();
+    }
+    unsafe { setnetent(NET_STAYOPEN) };
+    while {
+        n = unsafe { getnetent() };
+        !n.is_null()
+    } {
+        let n_ref = unsafe { &*n };
+        let mut addr_ptr = n_ref.n_net;
+        let mut matched = false;
+        if !addr_ptr.is_null() {
+            let stored = unsafe { *addr_ptr };
+            let stored_be = u32::from_be(stored);
+            matched = net == stored_be;
+        }
+        if matched {
+            unsafe { setnetent(NET_STAYOPEN) };
+            return n;
+        }
+    }
+    unsafe { setnetent(NET_STAYOPEN) };
+
+    platform::ERRNO.set(ENOENT);
+    ptr::null_mut::<netent>()
 }
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/endnetent.html>.
diff --git a/src/platform/redox/ptrace.rs b/src/platform/redox/ptrace.rs
index 51cb764683..4ac81a00c7 100644
--- a/src/platform/redox/ptrace.rs
+++ b/src/platform/redox/ptrace.rs
@@ -261,7 +261,10 @@ unsafe fn inner_ptrace(
             (&mut &session.regs).write(&redox_regs)?;
             Ok(0)
         }
-        _ => unimplemented!(),
+        _ => Err(io::Error::new(
+            io::ErrorKind::InvalidInput,
+            "unsupported ptrace request",
+        )),
     }
 }