diff --git a/README.md b/README.md
index dc078973..173310b5 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,14 @@
-libmdbx
+### IMPENDING CHANGES WARNING
+================================================================================
+
+**Now MDBX is under active development and until November 2017 is expected a big
+change both of API and database format.  Unfortunately those update will lead to
+loss of compatibility with previous versions.**
+
+The aim of this revolution in providing a clearer robust API and adding new
+features, including the database properties.
+
+libmdbx
 ======================================
 Extended LMDB, aka "Расширенная LMDB".
 
diff --git a/mdbx.h b/mdbx.h
index a35ffa79..4d95ae25 100644
--- a/mdbx.h
+++ b/mdbx.h
@@ -58,6 +58,15 @@
 #ifndef LIBMDBX_H
 #define LIBMDBX_H
 
+/* IMPENDING CHANGES WARNING ***************************************************
+ *
+ * Now MDBX is under active development and until November 2017 is expected a
+ * big change both of API and database format.  Unfortunately those update will
+ * lead to loss of compatibility with previous versions.
+ *
+ * The aim of this revolution in providing a clearer robust API and adding new
+ * features, including the database properties. */
+
 /*--------------------------------------------------------------------------*/
 
 #ifdef _MSC_VER