diff --git a/pyproject.toml b/pyproject.toml
index 0f3da126..b5dc8dc4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -69,6 +69,7 @@ dev = [
     {include-group = "test"},
 ]
 doc = [
+    "graphviz",
     "myst-nb",
     "sphinx",
     "sphinx-api-relink >=0.0.4",
diff --git a/uv.lock b/uv.lock
index 4e245d3d..ce1168f1 100644
--- a/uv.lock
+++ b/uv.lock
@@ -46,6 +46,7 @@ viz = [
 [package.dependency-groups]
 dev = [
     { name = "black" },
+    { name = "graphviz" },
     { name = "ipympl" },
     { name = "ipython" },
     { name = "ipywidgets" },
@@ -86,6 +87,7 @@ dev = [
 ]
 doc = [
     { name = "black" },
+    { name = "graphviz" },
     { name = "ipympl" },
     { name = "matplotlib" },
     { name = "mpl-interactions" },
@@ -164,6 +166,7 @@ requires-dist = [
 dev = [
     { name = "ampform", extras = ["scipy"] },
     { name = "black" },
+    { name = "graphviz" },
     { name = "ipympl" },
     { name = "ipython" },
     { name = "ipywidgets" },
@@ -206,6 +209,7 @@ dev = [
 ]
 doc = [
     { name = "black" },
+    { name = "graphviz" },
     { name = "ipympl" },
     { name = "matplotlib" },
     { name = "matplotlib", specifier = "<3.9.0" },