diff --git a/include/posix/unistd.h b/include/posix/unistd.h
index b789345a5eb..7af86fb5227 100644
--- a/include/posix/unistd.h
+++ b/include/posix/unistd.h
@@ -20,7 +20,7 @@ extern "C" {
  *
  * See IEEE 1003.1
  */
-static inline int sleep(unsigned int seconds)
+static inline unsigned sleep(unsigned int seconds)
 {
 	k_sleep(K_SECONDS(seconds));
 	return 0;