diff --git a/src/lib.rs b/src/lib.rs
index f01363dc..0b0a7671 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -326,7 +326,7 @@ pub struct SerialPortBuilder {
     /// Number of bits to use to signal the end of a character
     stop_bits: StopBits,
     /// Amount of time to wait to receive data before timing out
-    timeout: Duration,
+    timeout: Option<Duration>,
 }
 
 impl SerialPortBuilder {
@@ -375,7 +375,7 @@ impl SerialPortBuilder {
     /// Set the amount of time to wait to receive data before timing out
     #[must_use]
     pub fn timeout(mut self, timeout: Duration) -> Self {
-        self.timeout = timeout;
+        self.timeout = Some(timeout);
         self
     }
 
@@ -459,7 +459,7 @@ pub trait SerialPort: Send + io::Read + io::Write {
     fn stop_bits(&self) -> Result<StopBits>;
 
     /// Returns the current timeout.
-    fn timeout(&self) -> Duration;
+    fn timeout(&self) -> Option<Duration>;
 
     // Port settings setters
 
@@ -485,7 +485,7 @@ pub trait SerialPort: Send + io::Read + io::Write {
     fn set_stop_bits(&mut self, stop_bits: StopBits) -> Result<()>;
 
     /// Sets the timeout for future I/O operations.
-    fn set_timeout(&mut self, timeout: Duration) -> Result<()>;
+    fn set_timeout(&mut self, timeout: Option<Duration>) -> Result<()>;
 
     // Functions for setting non-data control signal pins
 
@@ -647,7 +647,7 @@ impl<T: SerialPort> SerialPort for &mut T {
         (**self).stop_bits()
     }
 
-    fn timeout(&self) -> Duration {
+    fn timeout(&self) -> Option<Duration> {
         (**self).timeout()
     }
 
@@ -671,7 +671,7 @@ impl<T: SerialPort> SerialPort for &mut T {
         (**self).set_stop_bits(stop_bits)
     }
 
-    fn set_timeout(&mut self, timeout: Duration) -> Result<()> {
+    fn set_timeout(&mut self, timeout: Option<Duration>) -> Result<()> {
         (**self).set_timeout(timeout)
     }
 
@@ -812,7 +812,7 @@ pub fn new<'a>(path: impl Into<std::borrow::Cow<'a, str>>, baud_rate: u32) -> Se
         flow_control: FlowControl::None,
         parity: Parity::None,
         stop_bits: StopBits::One,
-        timeout: Duration::from_millis(0),
+        timeout: None,
     }
 }
 
diff --git a/src/posix/poll.rs b/src/posix/poll.rs
index e45226ea..4cf0c656 100644
--- a/src/posix/poll.rs
+++ b/src/posix/poll.rs
@@ -11,32 +11,33 @@ use nix::sys::signal::SigSet;
 #[cfg(target_os = "linux")]
 use nix::sys::time::{TimeSpec, TimeValLike};
 
-pub fn wait_read_fd(fd: RawFd, timeout: Duration) -> io::Result<()> {
+pub fn wait_read_fd(fd: RawFd, timeout: Option<Duration>) -> io::Result<()> {
     wait_fd(fd, PollFlags::POLLIN, timeout)
 }
 
-pub fn wait_write_fd(fd: RawFd, timeout: Duration) -> io::Result<()> {
+pub fn wait_write_fd(fd: RawFd, timeout: Option<Duration>) -> io::Result<()> {
     wait_fd(fd, PollFlags::POLLOUT, timeout)
 }
 
-fn wait_fd(fd: RawFd, events: PollFlags, timeout: Duration) -> io::Result<()> {
+fn wait_fd(fd: RawFd, events: PollFlags, timeout: Option<Duration>) -> io::Result<()> {
     use nix::errno::Errno::{EIO, EPIPE};
 
     let mut fd = PollFd::new(fd, events);
 
-    let milliseconds =
-        timeout.as_secs() as i64 * 1000 + i64::from(timeout.subsec_nanos()) / 1_000_000;
+    let milliseconds = timeout.map(|t| t.as_secs() as i64 * 1000 +
+        i64::from(t.subsec_nanos()) / 1_000_000);
     #[cfg(target_os = "linux")]
     let wait_res = {
-        let timespec = TimeSpec::milliseconds(milliseconds);
+        let timespec = milliseconds.map(TimeSpec::milliseconds);
         nix::poll::ppoll(
             slice::from_mut(&mut fd),
-            Some(timespec),
+            timespec,
             Some(SigSet::empty()),
         )
     };
     #[cfg(not(target_os = "linux"))]
-    let wait_res = nix::poll::poll(slice::from_mut(&mut fd), milliseconds as nix::libc::c_int);
+    let wait_res =
+        nix::poll::poll(slice::from_mut(&mut fd), milliseconds.unwrap_or(-1) as nix::libc::c_int);
 
     let wait = match wait_res {
         Ok(r) => r,
diff --git a/src/posix/tty.rs b/src/posix/tty.rs
index b1d68cff..2beb1d17 100644
--- a/src/posix/tty.rs
+++ b/src/posix/tty.rs
@@ -60,7 +60,7 @@ fn close(fd: RawFd) {
 #[derive(Debug)]
 pub struct TTYPort {
     fd: RawFd,
-    timeout: Duration,
+    timeout: Option<Duration>,
     exclusive: bool,
     port_name: Option<String>,
     #[cfg(any(target_os = "ios", target_os = "macos"))]
@@ -311,7 +311,7 @@ impl TTYPort {
 
         let slave_tty = TTYPort {
             fd,
-            timeout: Duration::from_millis(100),
+            timeout: Some(Duration::from_millis(100)),
             exclusive: true,
             port_name: Some(ptty_name),
             #[cfg(any(target_os = "ios", target_os = "macos"))]
@@ -323,7 +323,7 @@ impl TTYPort {
         // BSDs when used on the master port.
         let master_tty = TTYPort {
             fd: next_pty_fd.into_raw_fd(),
-            timeout: Duration::from_millis(100),
+            timeout: Some(Duration::from_millis(100)),
             exclusive: true,
             port_name: None,
             #[cfg(any(target_os = "ios", target_os = "macos"))]
@@ -407,7 +407,7 @@ impl FromRawFd for TTYPort {
     unsafe fn from_raw_fd(fd: RawFd) -> Self {
         TTYPort {
             fd,
-            timeout: Duration::from_millis(100),
+            timeout: Some(Duration::from_millis(100)),
             exclusive: ioctl::tiocexcl(fd).is_ok(),
             // It is not trivial to get the file path corresponding to a file descriptor.
             // We'll punt on it and set it to `None` here.
@@ -616,7 +616,7 @@ impl SerialPort for TTYPort {
         }
     }
 
-    fn timeout(&self) -> Duration {
+    fn timeout(&self) -> Option<Duration> {
         self.timeout
     }
 
@@ -678,7 +678,7 @@ impl SerialPort for TTYPort {
         return termios::set_termios(self.fd, &termios);
     }
 
-    fn set_timeout(&mut self, timeout: Duration) -> Result<()> {
+    fn set_timeout(&mut self, timeout: Option<Duration>) -> Result<()> {
         self.timeout = timeout;
         Ok(())
     }