diff --git a/ChangeLog b/ChangeLog
index 81c4f2786..91242c573 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2013-12-16  Vladimir Serbinenko  <phcoder@gmail.com>
+
+	* grub-core/lib/posix_wrap/errno.h: Undefine errno before redefining.
+
 2013-12-16  Vladimir Serbinenko  <phcoder@gmail.com>
 
 	* include/grub/efi/api.h: Define (u)intn_t based on pointer size and
diff --git a/grub-core/lib/posix_wrap/errno.h b/grub-core/lib/posix_wrap/errno.h
index 9031722e2..ba63b2366 100644
--- a/grub-core/lib/posix_wrap/errno.h
+++ b/grub-core/lib/posix_wrap/errno.h
@@ -21,6 +21,7 @@
 
 #include <grub/err.h>
 
+#undef errno
 #define errno  grub_errno
 #define EINVAL GRUB_ERR_BAD_NUMBER
 #define ENOMEM GRUB_ERR_OUT_OF_MEMORY