diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0f1c7fe..d9c524f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [unreleased]
 
+## [1.9.0] - 2021-08-27
+
 ### Added
 
  - `metalang99.h`:
diff --git a/Doxyfile b/Doxyfile
index 6bb886a..19de8ff 100644
--- a/Doxyfile
+++ b/Doxyfile
@@ -38,7 +38,7 @@ PROJECT_NAME           = "Metalang99"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 1.8.0
+PROJECT_NUMBER         = 1.9.0
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
diff --git a/docs/conf.py b/docs/conf.py
index 128babb..1e35082 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -25,7 +25,7 @@
 author = 'Hirrolot'
 
 # The full version, including alpha/beta/rc tags
-release = '1.8.0'
+release = '1.9.0'
 
 
 # -- General configuration ---------------------------------------------------
diff --git a/include/metalang99.h b/include/metalang99.h
index b748022..20456c0 100644
--- a/include/metalang99.h
+++ b/include/metalang99.h
@@ -19,7 +19,7 @@
 #include <metalang99/variadics.h>
 
 #define ML99_MAJOR 1
-#define ML99_MINOR 8
+#define ML99_MINOR 9
 #define ML99_PATCH 0
 
 #define ML99_VERSION_COMPATIBLE(x, y, z)                                                           \
diff --git a/spec/spec.pdf b/spec/spec.pdf
index 549d16d..7aa1f4e 100644
Binary files a/spec/spec.pdf and b/spec/spec.pdf differ
diff --git a/spec/spec.tex b/spec/spec.tex
index 6de6d34..7194c64 100644
--- a/spec/spec.tex
+++ b/spec/spec.tex
@@ -24,7 +24,7 @@
 
 \begin{document}
 
-\title{Metalang99 Specification (v1.8.0)}
+\title{Metalang99 Specification (v1.9.0)}
 \date{\today}
 \author{Hirrolot \\ e-mail: \href{mailto:hirrolot@gmail.com}{hirrolot@gmail.com}}
 \maketitle