diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index a139eb8..0a93487 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -13,6 +13,7 @@ collect (PROJECT_LIB_HEADERS condition.h)
 collect (PROJECT_LIB_HEADERS config.h)
 collect (PROJECT_LIB_HEADERS cpu.h)
 collect (PROJECT_LIB_HEADERS device.h)
+collect (PROJECT_LIB_HEADERS errno.h)
 collect (PROJECT_LIB_HEADERS dma.h)
 collect (PROJECT_LIB_HEADERS io.h)
 collect (PROJECT_LIB_HEADERS irq.h)
diff --git a/lib/compiler/iar/CMakeLists.txt b/lib/compiler/iar/CMakeLists.txt
index 831ca70..3dbec5c 100644
--- a/lib/compiler/iar/CMakeLists.txt
+++ b/lib/compiler/iar/CMakeLists.txt
@@ -1,3 +1,4 @@
 collect (PROJECT_LIB_HEADERS compiler.h)
+collect (PROJECT_LIB_HEADERS errno.h)
 
 # vim: expandtab:ts=2:sw=2:smartindent
diff --git a/lib/compiler/iar/errno.h b/lib/compiler/iar/errno.h
new file mode 100644
index 0000000..69cd86c
--- /dev/null
+++ b/lib/compiler/iar/errno.h
@@ -0,0 +1,60 @@
+/*-
+ * Copyright (c) 2020 STMicroelectronics. All rights reserved.
+ *
+ * Copyright (c) 1982, 1986, 1989, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ * (c) UNIX System Laboratories, Inc.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __METAL_IAR_ERRNO__H__
+#define __METAL_IAR_ERRNO__H__
+
+#include <errno.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define LIBMETAL_ERR_BASE  100
+
+#define	EPERM	(LIBMETAL_ERR_BASE + 1)  /* Operation not permitted */
+#define	ENOENT	(LIBMETAL_ERR_BASE + 2)  /* No such file or directory */
+#define	ESRCH	(LIBMETAL_ERR_BASE + 3)  /* No such process */
+#define	EINTR	(LIBMETAL_ERR_BASE + 4)  /* Interrupted system call */
+#define	EIO	(LIBMETAL_ERR_BASE + 5)  /* Input/output error */
+#define	ENXIO	(LIBMETAL_ERR_BASE + 6)  /* Device not configured */
+#define	E2BIG	(LIBMETAL_ERR_BASE + 7)  /* Argument list too long */
+#define	ENOEXEC	(LIBMETAL_ERR_BASE + 8)  /* Exec format error */
+#define	EBADF	(LIBMETAL_ERR_BASE + 9)  /* Bad file descriptor */
+#define	ECHILD	(LIBMETAL_ERR_BASE + 10) /* No child processes */
+#define	EDEADLK	(LIBMETAL_ERR_BASE + 11) /* Resource deadlock avoided */
+#define	ENOMEM	(LIBMETAL_ERR_BASE + 12) /* Cannot allocate memory */
+#define	EACCES	(LIBMETAL_ERR_BASE + 13) /* Permission denied */
+#define	EFAULT	(LIBMETAL_ERR_BASE + 14) /* Bad address */
+#define	ENOTBLK	(LIBMETAL_ERR_BASE + 15) /* Block device required */
+#define	EBUSY	(LIBMETAL_ERR_BASE + 16) /* Device busy */
+#define	EEXIST	(LIBMETAL_ERR_BASE + 17) /* File exists */
+#define	EXDEV	(LIBMETAL_ERR_BASE + 18) /* Cross-device link */
+#define	ENODEV	(LIBMETAL_ERR_BASE + 19) /* Operation not supported by device */
+#define	ENOTDIR	(LIBMETAL_ERR_BASE + 20) /* Not a directory */
+#define	EISDIR	(LIBMETAL_ERR_BASE + 21) /* Is a directory */
+#define	EINVAL	(LIBMETAL_ERR_BASE + 22) /* Invalid argument */
+#define	ENFILE	(LIBMETAL_ERR_BASE + 23) /* Too many open files in system */
+#define	EMFILE	(LIBMETAL_ERR_BASE + 24) /* Too many open files */
+#define	ENOTTY	(LIBMETAL_ERR_BASE + 25) /* Inappropriate ioctl for device */
+#define	ETXTBSY	(LIBMETAL_ERR_BASE + 26) /* Text file busy */
+#define	EFBIG	(LIBMETAL_ERR_BASE + 27) /* File too large */
+#define	ENOSPC	(LIBMETAL_ERR_BASE + 28) /* No space left on device */
+#define	ESPIPE	(LIBMETAL_ERR_BASE + 29) /* Illegal seek */
+#define	EROFS	(LIBMETAL_ERR_BASE + 30) /* Read-only filesystem */
+#define	EMLINK	(LIBMETAL_ERR_BASE + 31) /* Too many links */
+#define	EPIPE	(LIBMETAL_ERR_BASE + 32) /* Broken pipe */
+#define	EAGAIN	(LIBMETAL_ERR_BASE + 35) /* Resource temporarily unavailable */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __METAL_IAR_ERRNO__H__ */
diff --git a/lib/errno.h b/lib/errno.h
new file mode 100644
index 0000000..fb4997e
--- /dev/null
+++ b/lib/errno.h
@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2020 STMicroelectronnics. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+/*
+ * @file      metal/errno.h
+ * @brief     error specific primitives for libmetal.
+ */
+
+#ifndef __METAL_ERRNO__H__
+#define __METAL_ERRNO__H__
+
+#if defined(__ICCARM__)
+# include <metal/compiler/iar/errno.h>
+#else
+# include <errno.h>
+#endif
+
+#endif /* __METAL_ERRNO__H__ */