diff --git a/libc-test/semver/unix.txt b/libc-test/semver/unix.txt
index 052c24178dfc..6d23ae433855 100644
--- a/libc-test/semver/unix.txt
+++ b/libc-test/semver/unix.txt
@@ -359,6 +359,7 @@ SO_SNDBUF
 SO_SNDLOWAT
 SO_SNDTIMEO
 SO_TYPE
+SSIZE_MAX
 STDERR_FILENO
 STDIN_FILENO
 STDOUT_FILENO
diff --git a/src/unix/mod.rs b/src/unix/mod.rs
index ff440d5a13f1..58dbe9c4db72 100644
--- a/src/unix/mod.rs
+++ b/src/unix/mod.rs
@@ -247,6 +247,8 @@ cfg_if! {
 pub const INT_MIN: c_int = -2147483648;
 pub const INT_MAX: c_int = 2147483647;
 
+pub const SSIZE_MAX: ssize_t = ssize_t::MAX;
+
 pub const SIG_DFL: sighandler_t = 0 as sighandler_t;
 pub const SIG_IGN: sighandler_t = 1 as sighandler_t;
 pub const SIG_ERR: sighandler_t = !0 as sighandler_t;