diff --git a/daemon/src/lib.rs b/daemon/src/lib.rs
index 9f507221..2d092b0b 100644
--- a/daemon/src/lib.rs
+++ b/daemon/src/lib.rs
@@ -10,15 +10,35 @@ use libredox::Fd;
 use redox_scheme::Socket;
 use redox_scheme::scheme::{SchemeAsync, SchemeSync};
 
-unsafe fn get_fd(var: &str) -> RawFd {
-    let fd: RawFd = std::env::var(var).unwrap().parse().unwrap();
+unsafe fn get_fd(var: &str) -> Option<RawFd> {
+    let value = match std::env::var(var) {
+        Ok(value) => value,
+        Err(_) => {
+            let exe = std::env::args()
+                .next()
+                .unwrap_or_else(|| "daemon".to_string());
+            eprintln!("daemon: {var} not set for {exe}; readiness notification disabled");
+            return None;
+        }
+    };
+    let fd: RawFd = match value.parse() {
+        Ok(fd) => fd,
+        Err(err) => {
+            let exe = std::env::args()
+                .next()
+                .unwrap_or_else(|| "daemon".to_string());
+            eprintln!("daemon: invalid {var} value {value:?} for {exe}: {err}; readiness notification disabled");
+            return None;
+        }
+    };
     if unsafe { libc::fcntl(fd, libc::F_SETFD, libc::FD_CLOEXEC) } == -1 {
-        panic!(
+        eprintln!(
             "daemon: failed to set CLOEXEC flag for {var} fd: {}",
             io::Error::last_os_error()
         );
+        return None;
     }
-    fd
+    Some(fd)
 }
 
 unsafe fn pass_fd(cmd: &mut Command, env: &str, fd: OwnedFd) {
@@ -38,20 +58,22 @@ unsafe fn pass_fd(cmd: &mut Command, env: &str, fd: OwnedFd) {
 /// A long running background process that handles requests.
 #[must_use = "Daemon::ready must be called"]
 pub struct Daemon {
-    write_pipe: PipeWriter,
+    write_pipe: Option<PipeWriter>,
 }
 
 impl Daemon {
     /// Create a new daemon.
     pub fn new(f: impl FnOnce(Daemon) -> !) -> ! {
-        let write_pipe = unsafe { io::PipeWriter::from_raw_fd(get_fd("INIT_NOTIFY")) };
+        let write_pipe = get_fd("INIT_NOTIFY").map(|fd| unsafe { io::PipeWriter::from_raw_fd(fd) });
 
         f(Daemon { write_pipe })
     }
 
     /// Notify the process that the daemon is ready to accept requests.
     pub fn ready(mut self) {
-        self.write_pipe.write_all(&[0]).unwrap();
+        if let Some(write_pipe) = self.write_pipe.as_mut() {
+            write_pipe.write_all(&[0]).unwrap();
+        }
     }
 
     /// Executes `Command` as a child process.
@@ -83,21 +105,25 @@ impl Daemon {
 /// A long running background process that handles requests using schemes.
 #[must_use = "SchemeDaemon::ready must be called"]
 pub struct SchemeDaemon {
-    write_pipe: PipeWriter,
+    write_pipe: Option<PipeWriter>,
 }
 
 impl SchemeDaemon {
     /// Create a new daemon for use with schemes.
     pub fn new(f: impl FnOnce(SchemeDaemon) -> !) -> ! {
-        let write_pipe = unsafe { io::PipeWriter::from_raw_fd(get_fd("INIT_NOTIFY")) };
+        let write_pipe = get_fd("INIT_NOTIFY").map(|fd| unsafe { io::PipeWriter::from_raw_fd(fd) });
 
         f(SchemeDaemon { write_pipe })
     }
 
     /// Notify the process that the scheme daemon is ready to accept requests.
     pub fn ready_with_fd(self, cap_fd: Fd) -> syscall::Result<()> {
+        let write_pipe = match self.write_pipe {
+            Some(pipe) => pipe,
+            None => return Ok(()),
+        };
         syscall::call_wo(
-            self.write_pipe.as_raw_fd() as usize,
+            write_pipe.as_raw_fd() as usize,
             &cap_fd.into_raw().to_ne_bytes(),
             syscall::CallFlags::FD,
             &[],