diff --git a/README.md b/README.md
index 214f7ad..d524665 100644
--- a/README.md
+++ b/README.md
@@ -17,6 +17,7 @@ Requirements:
 * numpy
 * matplotlib (optional, used for `visualization` functions and `text`)
 * python-gdsii (optional, used for `gdsii` i/o)
+* klamath (optional, used for `gdsii` i/o and library management)
 * ezdxf (optional, used for `dxf` i/o)
 * fatamorgana (optional, used for `oasis` i/o)
 * svgwrite (optional, used for `svg` output)
@@ -25,7 +26,7 @@ Requirements:
 
 Install with pip:
 ```bash
-pip3 install 'masque[visualization,gdsii,oasis,dxf,svg,text]'
+pip3 install 'masque[visualization,gdsii,oasis,dxf,svg,text,klamath]'
 ```
 
 Alternatively, install from git
diff --git a/setup.py b/setup.py
index 1d3138b..ff8aad9 100644
--- a/setup.py
+++ b/setup.py
@@ -28,6 +28,7 @@ setup(name='masque',
       ],
       extras_require={
           'gdsii': ['python-gdsii'],
+          'klamath': ['klamath'],
           'oasis': ['fatamorgana>=0.7'],
           'dxf': ['ezdxf'],
           'svg': ['svgwrite'],