diff --git a/RELEASE-NOTES.md b/RELEASE-NOTES.md
index 6386028e..05a1869c 100644
--- a/RELEASE-NOTES.md
+++ b/RELEASE-NOTES.md
@@ -1,6 +1,6 @@
 # Wikibase DataModel release notes
 
-## Version 4.0 (dev)
+## Version 4.0 (2015-07-28)
 
 #### Breaking changes
 
diff --git a/WikibaseDataModel.php b/WikibaseDataModel.php
index dbf3e56c..324c1ad2 100644
--- a/WikibaseDataModel.php
+++ b/WikibaseDataModel.php
@@ -12,7 +12,7 @@
 	return 1;
 }
 
-define( 'WIKIBASE_DATAMODEL_VERSION', '3.0.1' );
+define( 'WIKIBASE_DATAMODEL_VERSION', '4.0.0' );
 
 if ( defined( 'MEDIAWIKI' ) ) {
 	call_user_func( function() {