diff --git a/docs/Changelog.md b/docs/Changelog.md
index afb9dea6..57b2b4a2 100644
--- a/docs/Changelog.md
+++ b/docs/Changelog.md
@@ -9,6 +9,10 @@ Want to stay in the loop on major new features? Join our mailing list by
 sending a mail to <afl-users+subscribe@googlegroups.com>.
 
 
+### Version ++2.66d (devel)
+  - ... ?
+
+
 ### Version ++2.66c (release)
   - renamed the main branch on Github to "stable"
   - renamed master/slave to main/secondary
diff --git a/include/config.h b/include/config.h
index e8f52f45..7de74009 100644
--- a/include/config.h
+++ b/include/config.h
@@ -28,7 +28,7 @@
 /* Version string: */
 
 // c = release, d = volatile github dev, e = experimental branch
-#define VERSION "++2.66c"
+#define VERSION "++2.66d"
 
 /******************************************************
  *                                                    *