diff --git a/include/posix/unistd.h b/include/posix/unistd.h
index 7af86fb5227..e3c6b69dab0 100644
--- a/include/posix/unistd.h
+++ b/include/posix/unistd.h
@@ -10,39 +10,16 @@
 extern "C" {
 #endif
 
-#include_next <unistd.h>
-
-#ifdef CONFIG_PTHREAD_IPC
 #include "sys/types.h"
 
-/**
- * @brief Sleep for a specified number of seconds.
- *
- * See IEEE 1003.1
- */
-static inline unsigned sleep(unsigned int seconds)
-{
-	k_sleep(K_SECONDS(seconds));
-	return 0;
-}
-/**
- * @brief Suspend execution for microsecond intervals.
- *
- * See IEEE 1003.1
- */
-static inline int usleep(useconds_t useconds)
-{
-	if (useconds < USEC_PER_MSEC) {
-		k_busy_wait(useconds);
-	} else {
-		k_sleep(useconds / USEC_PER_MSEC);
-	}
+#ifndef __ZEPHYR__
+#include_next <unistd.h>
+#endif
 
-	return 0;
-}
+unsigned sleep(unsigned int seconds);
+int usleep(useconds_t useconds);
 
 #endif
 #ifdef __cplusplus
 }
-#endif
 #endif	/* __POSIX_UNISTD_H__ */
diff --git a/kernel/posix/CMakeLists.txt b/kernel/posix/CMakeLists.txt
index 0ecc735142e..88788086d1c 100644
--- a/kernel/posix/CMakeLists.txt
+++ b/kernel/posix/CMakeLists.txt
@@ -5,6 +5,7 @@ target_sources(kernel PRIVATE posix/pthread_barrier.c)
 target_sources(kernel PRIVATE posix/pthread.c)
 target_sources(kernel PRIVATE posix/pthread_sched.c)
 target_sources(kernel PRIVATE posix/clock.c)
+target_sources(kernel PRIVATE posix/sleep.c)
 target_sources(kernel PRIVATE posix/timer.c)
 target_sources(kernel PRIVATE posix/pthread_rwlock.c)
 target_sources(kernel PRIVATE posix/semaphore.c)
diff --git a/kernel/posix/sleep.c b/kernel/posix/sleep.c
new file mode 100644
index 00000000000..6cbd36d52bd
--- /dev/null
+++ b/kernel/posix/sleep.c
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2018 Intel Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include <unistd.h>
+
+/**
+ * @brief Sleep for a specified number of seconds.
+ *
+ * See IEEE 1003.1
+ */
+unsigned sleep(unsigned int seconds)
+{
+	k_sleep(K_SECONDS(seconds));
+	return 0;
+}
+/**
+ * @brief Suspend execution for microsecond intervals.
+ *
+ * See IEEE 1003.1
+ */
+int usleep(useconds_t useconds)
+{
+	if (useconds < USEC_PER_MSEC) {
+		k_busy_wait(useconds);
+	} else {
+		k_sleep(useconds / USEC_PER_MSEC);
+	}
+
+	return 0;
+}