diff --git a/library/std/src/sys/random/arc4random.rs b/library/std/src/sys/random/arc4random.rs
index 32467e9ebaa64..ffabaafbee803 100644
--- a/library/std/src/sys/random/arc4random.rs
+++ b/library/std/src/sys/random/arc4random.rs
@@ -12,6 +12,7 @@
 #[cfg(not(any(
     target_os = "haiku",
     target_os = "illumos",
+    target_os = "rtems",
     target_os = "solaris",
     target_os = "vita",
 )))]
@@ -21,6 +22,7 @@ use libc::arc4random_buf;
 #[cfg(any(
     target_os = "haiku", // See https://git.haiku-os.org/haiku/tree/headers/compatibility/bsd/stdlib.h
     target_os = "illumos", // See https://www.illumos.org/man/3C/arc4random
+    target_os = "rtems", // See https://docs.rtems.org/branches/master/bsp-howto/getentropy.html
     target_os = "solaris", // See https://docs.oracle.com/cd/E88353_01/html/E37843/arc4random-3c.html
     target_os = "vita", // See https://github.com/vitasdk/newlib/blob/b89e5bc183b516945f9ee07eef483ecb916e45ff/newlib/libc/include/stdlib.h#L74
 ))]
diff --git a/library/std/src/sys/random/mod.rs b/library/std/src/sys/random/mod.rs
index d625814d15b39..edc2cacdfd874 100644
--- a/library/std/src/sys/random/mod.rs
+++ b/library/std/src/sys/random/mod.rs
@@ -17,6 +17,7 @@ cfg_if::cfg_if! {
         target_os = "illumos",
         target_os = "netbsd",
         target_os = "openbsd",
+        target_os = "rtems",
         target_os = "solaris",
         target_os = "vita",
     ))] {