diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8f953889..036eb8a9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,23 @@ for the source-code artifacts of each version.
 
 ## Pynguin 0.13.0
 
+- Add an assertion-generation strategy based on mutation (thanks to @f-str).
+
+  The new strategy is enabled by default (can be configured using the 
+  `--assertion-generation` parameter).  It uses a custom
+  [fork](https://github.com/se2p/mutpy-pynguin) of the mutation-testing framework
+  [MutPy](https://github.com/mutpy/mutpy), which mutates the subject under test and for
+  each mutant traces the values of fields and returned by method calls.  If these values
+  differ between mutant and original code, an assertion is generated based on the result
+  on the original subject under test.  One can also control whether the strategy shall
+  also generate assertions for unchanged values by the `--generate-all-assertions` flag.
+
+  The release also updates the documentation accordingly.
+
+  *Note:* This feature is an early prototype of such an assertion generation, which 
+  might cause unexpected behaviour.  You can switch back to the previous strategy for
+  assertion generation by setting `--assertion-generation SIMPLE`.
+
 ## Pynguin 0.12.0
 
 - Generate more reasonable variable names in tests.
diff --git a/docker/Dockerfile b/docker/Dockerfile
index 6c96a7b8..3dce2532 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -36,7 +36,7 @@ FROM python:3.9.7-slim-bullseye AS execute
 
 # Set environment variables
 # Set the Pynguin version
-ENV PYNGUIN_VERSION "0.13.0.dev0"
+ENV PYNGUIN_VERSION "0.13.0"
 # Pynguin requires to set the variable to show it that the user is aware that running
 # Pynguin executes third-party code, which could cause arbitrary harm to the system.
 # By setting the variable, the user acknowledges that they are aware of this.  In the
diff --git a/pynguin/__init__.py b/pynguin/__init__.py
index 06e2847a..723814ca 100644
--- a/pynguin/__init__.py
+++ b/pynguin/__init__.py
@@ -17,7 +17,7 @@
 StoppingCondition = config.StoppingCondition
 TypeInferenceStrategy = config.TypeInferenceStrategy
 
-__version__ = "0.13.0.dev"
+__version__ = "0.13.0"
 __all__ = [
     "set_configuration",
     "run_pynguin",
diff --git a/pyproject.toml b/pyproject.toml
index 7a787da1..a57714c4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@
 
 [tool.poetry]
 name = "pynguin"
-version = "0.13.0.dev"
+version = "0.13.0"
 description = "Pynguin is a tool for automated unit test generation for Python"
 authors = ["Stephan Lukasczyk <stephan@lukasczyk.me>"]
 license = "LGPL-3.0-or-later"