diff --git a/src/private_openat.c b/src/private_openat.c
new file mode 100644
index 0000000..9f5fe78
--- /dev/null
+++ b/src/private_openat.c
@@ -0,0 +1,22 @@
+
+#include <fcntl.h>
+#include <string.h>
+#include <stdio.h>
+
+#include "private_openat.h"
+
+
+int private_openat(int directory_file_descriptor, const char* path_name, int flags)
+{
+	int file_descriptor;
+
+	char full_path[MAX_PATH_LEN];
+
+	fcntl(directory_file_descriptor, F_GETPATH, full_path);
+	strlcat(full_path, "/", MAX_PATH_LEN);
+	strlcat(full_path, path_name, MAX_PATH_LEN);
+
+	file_descriptor = open(full_path, flags);
+
+	return file_descriptor;
+}
diff --git a/src/private_openat.h b/src/private_openat.h
new file mode 100644
index 0000000..07c40dc
--- /dev/null
+++ b/src/private_openat.h
@@ -0,0 +1,27 @@
+/**
+ * @file private_openat.h
+ * @author Celine Mercier
+ * @date 15 June 2015
+ * @brief Header file for a replacement function for openat.
+ */
+
+#ifndef PRIVATE_OPENAT_H_
+#define PRIVATE_OPENAT_H_
+
+#define MAX_PATH_LEN 4096
+
+/**
+ * @brief Replacement function for openat() : open a file relative to a directory file descriptor.
+ *
+ * @param directory_file_descriptor the file descriptor for the directory in which the file should be opened
+ * @param path_name the path name for the file, relative to directory_file_descriptor
+ * @param flags the access modes
+ *
+ * @return the file descriptor of the opened file
+ *
+ * @since June 2015
+ * @author Celine Mercier (celine.mercier@metabarcoding.org)
+ */
+int private_openat(int directory_file_descriptor, const char* path_name, int flags);
+
+#endif /* PRIVATEOPENAT_H_ */