diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index e6e62f1..8e895a3 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -15,6 +15,7 @@ Breaking changes
 ================
 * The `bed_variant_call_regions` option has been removed, variants are now
   called for all genes present in the `gtf` file.
+* Add graphviz/`dot` as a dependency (developer only).
 
 Novel module
 ============
diff --git a/environment.yml b/environment.yml
index 3d04854..6b90456 100644
--- a/environment.yml
+++ b/environment.yml
@@ -15,3 +15,4 @@ dependencies:
   - sphinx=7.1.2
   - sphinx-rtd-theme
   - pysam=0.22
+  - graphviz