diff --git a/mdadm.h b/mdadm.h
index d754730..bfeddd0 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -1040,6 +1040,7 @@ extern char *conf_word(FILE *file, int allow_key);
 extern int conf_name_is_free(char *name);
 extern int devname_matches(char *name, char *match);
 extern struct mddev_ident *conf_match(struct mdinfo *info, struct supertype *st);
+extern int experimental(void);
 
 extern void free_line(char *line);
 extern int match_oneof(char *devices, char *devname);
diff --git a/util.c b/util.c
index fde58eb..4b41e2b 100644
--- a/util.c
+++ b/util.c
@@ -1896,3 +1896,13 @@ void append_metadata_update(struct supertype *st, void *buf, int len)
 unsigned int __invalid_size_argument_for_IOC = 0;
 #endif
 
+int experimental(void)
+{
+	if (check_env("MDADM_EXPERIMENTAL"))
+		return 1;
+	else {
+		fprintf(stderr, Name ": To use this feature MDADM_EXPERIMENTAL enviroment variable has to defined.\n");
+		return 0;
+	}
+}
+