diff --git a/CHANGELOG.rst b/CHANGELOG.rst
new file mode 100644
index 0000000..38a8675
--- /dev/null
+++ b/CHANGELOG.rst
@@ -0,0 +1,19 @@
+Changes in `1.0.0 <http://matrix.org/git/olm/commit/?h=1.0.0>`_
+===============================================================
+
+This release includes a fix to a bug which had the potential to leak sensitive
+data to the application: see
+https://github.com/vector-im/vector-web/issues/1719. Users of pre-1.x.x
+versions of the Olm library should upgrade. Our thanks to `Dmitry Luyciv
+<https://github.com/dluciv>`_ for bringing our attention to the bug.
+
+Other changes since 0.1.0:
+
+ * *Experimental* implementation of the primitives for group sessions. This
+   implementation has not yet been used in an application and developers are
+   advised not to rely on its stability.
+
+ * Replace custom build scripts with a Makefile.
+
+ * Include the major version number in the soname of libolm.so (credit to
+   Emmanuel Gil Peyrot).
diff --git a/Makefile b/Makefile
index 18230f7..2bfd2ab 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 #!/usr/bin/make -f
 
-MAJOR := 0
-MINOR := 1
+MAJOR := 1
+MINOR := 0
 PATCH := 0
 VERSION := $(MAJOR).$(MINOR).$(PATCH)
 PREFIX ?= /usr/local
diff --git a/javascript/package.json b/javascript/package.json
index 710d46d..17c2096 100644
--- a/javascript/package.json
+++ b/javascript/package.json
@@ -1,6 +1,6 @@
 {
   "name": "olm",
-  "version": "0.1.0",
+  "version": "1.0.0",
   "description": "An implementation of a well known cryptographic ratchet",
   "main": "olm.js",
   "files": [