diff --git a/.github/ISSUE_TEMPLATE/release.md b/.github/ISSUE_TEMPLATE/release.md
index 366fa6d28..b8e2569e5 100644
--- a/.github/ISSUE_TEMPLATE/release.md
+++ b/.github/ISSUE_TEMPLATE/release.md
@@ -1,6 +1,5 @@
 # OpenSlide release process
 
-- [ ] Check CI for build and test failures.  Check all mosaics.
 - [ ] Update `CHANGELOG.md` and `version` and `soversion` in `meson.build`
 - [ ] Create and push signed tag
 - [ ] Ensure Meson version is at least 0.60
@@ -9,6 +8,7 @@
 - [ ] [Update openslide-winbuild](https://github.com/openslide/openslide-winbuild/issues/new?labels=release&template=release.md)
 - [ ] Update website: `_data/releases.yaml`, `_includes/news.md`, `api/`
 - [ ] Start a [CI build](https://github.com/openslide/openslide.github.io/actions/workflows/retile.yml) of the demo site
+- [ ] Update Ubuntu PPA
 - [ ] Send mail to -announce and -users
 - [ ] Update Fedora and EPEL packages
 - [ ] Update MacPorts package
diff --git a/CHANGELOG.md b/CHANGELOG.md
index fd8ce30f5..a026922d5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,56 @@
 # Notable Changes in OpenSlide
 
 
+## Version 4.0.0, 2023-10-11
+
+### Breaking changes
+
+* Update soname to `libopenslide.so.1`
+* Remove all deprecated functions
+* Clear `openslide_read_associated_image()` output buffer on error
+* Remove undocumented NULL `dest` support in `openslide_read_associated_image()`
+* Change GLib log domain to `OpenSlide`
+* Convert build system to Meson (thanks, Jan Harkes)
+
+### New features
+
+* New format: DICOM WSI (thanks, John Cupitt and Jim O'Donnell)
+* Add APIs to read ICC color profiles (thanks, John)
+* Add APIs to configure tile cache size and share caches between slides
+* Add properties for associated image metadata
+* generic-tiff: Set MPP properties if available
+* philips: Set objective power property if available
+* Add `slidetool` command-line tool which supports all OpenSlide features
+* Combine all command-line tools into the same binary
+* Add ICC profile to PNG images written by command-line tools
+* Add self-test that doesn't require sample data (run with `meson test`)
+
+### Changes
+
+* Require libtiff ≥ 4, OpenJPEG ≥ 2.1, GLib ≥ 2.56, SQLite ≥ 3.14
+* Require libdicom ≥ 1.0, with build-time fallback for now
+* Remove support for including `openslide.h` in Visual Studio \< 2013
+* Fail `openslide_open()` with a broken pixman 0.38.x
+* Avoid extra buffer copy in `openslide_read_region()`
+* Replace `goto`-based cleanup with `g_autoptr`
+* Stop using deprecated GLib slice allocator
+* Use internal wrappers for file I/O
+* Documentation improvements
+
+### Bug fixes
+
+* Use UTF-8 filenames on Windows
+* Improve `openslide-write-png` performance for very large regions
+* Fix assertions on JPEG decode errors when compiled with Clang
+* Portability fixes (thanks, Billy Robert O'Neal III and Kleis Auke Wolthuizen)
+* aperio: Set objective power property even if floating point
+* hamamatsu: Fix `Restart marker not found` on VMS slides with multiple Z-layers
+* hamamatsu: Fix integer overflow in VMS parsing (thanks, Adam Goode)
+* mirax: Fix `Expected 1 value` error
+* philips: Don't cache missing tiles
+* sakura: Fix memory leak reading missing tile
+
+
 ## Version 3.4.1, 2015-04-20
 
 * New formats: Philips TIFF, Ventana TIFF
@@ -13,7 +63,7 @@
 * aperio: Detect OpenJPEG chroma subsampling breakage during `open`
 * aperio: Fill in missing tiles with downsampled data
 * aperio: Report MPP for slides scanned in locales with decimal comma
-* hamamatsu: Support NDPI files &gt; 4 GB
+* hamamatsu: Support NDPI files \> 4 GB
 * hamamatsu: Properly detect NDPI slides produced by NDP.toolkit
 * hamamatsu: Support VMS/VMU slides without a `NoLayers` key
 * hamamatsu: Report MPP for VMS/VMU
@@ -74,7 +124,7 @@
 
 ## Version 3.3.0, 2012-09-08
 
-* Support Leica SCN format (requires libtiff &ge; 4) (thanks, Agelos Pappas)
+* Support Leica SCN format (requires libtiff ≥ 4) (thanks, Agelos Pappas)
 * Allow opening MIRAX 2.2 slides (though there are seams, bug #92)
 * Add standardized microns-per-pixel and objective-power properties
 * Add `macro` associated image in Trestle
@@ -93,7 +143,7 @@
 
 * Support downsampled MIRAX files
 * Improve performance on MIRAX slides without tile overlaps
-* Fix `openslide_read_region` for large dimensions on layer &gt; 0
+* Fix `openslide_read_region` for large dimensions on layer \> 0
   (3.2.5 regression)
 * Correct subpixel error in MIRAX tile placement
 * Fix unlikely use-after-free with Hamamatsu VMU
diff --git a/README.md b/README.md
index d0adb36fe..423455ca6 100644
--- a/README.md
+++ b/README.md
@@ -63,16 +63,16 @@ more details.
 To build OpenSlide, you will need:
 
 - Meson
-- cairo &ge; 1.2
+- cairo ≥ 1.2
 - GDK-PixBuf
-- glib &ge; 2.56
-- libdicom &ge; 1.0 (automatically built if missing)
+- glib ≥ 2.56
+- libdicom ≥ 1.0 (automatically built if missing)
 - libjpeg
 - libpng
-- libtiff &ge; 4.0
+- libtiff ≥ 4.0
 - libxml2
-- OpenJPEG &ge; 2.1
-- SQLite &ge; 3.14
+- OpenJPEG ≥ 2.1
+- SQLite ≥ 3.14
 - zlib
 
 Then:
diff --git a/meson.build b/meson.build
index 50291b7db..0b4d7d47b 100644
--- a/meson.build
+++ b/meson.build
@@ -1,6 +1,6 @@
 project(
   'openslide', 'c',
-  version : '3.4.1',
+  version : '4.0.0',
   license : 'LGPL-2.1-only',
   default_options : [
     'buildtype=debugoptimized',
@@ -10,9 +10,8 @@ project(
   # limited by Ubuntu 20.04
   meson_version : '>=0.53',
 )
-# Shared library version.  Follow SemVer rules, except that major 0 isn't
-# special.
-soversion = '0.4.1'
+# Shared library version.  Follow SemVer rules.
+soversion = '1.0.0'
 
 if not meson.is_subproject()
   meson.add_dist_script(