diff --git a/environment.yml b/environment.yml
index ee13527..a6e5861 100644
--- a/environment.yml
+++ b/environment.yml
@@ -17,9 +17,11 @@ name: skywater-pdk-scripts
 channels:
 - symbiflow
 - defaults
+- conda-forge
 dependencies:
 - python=3.8
 - pip
+- ngspice
 # Packages installed from PyPI
 - pip:
   - -r file:requirements.txt
diff --git a/requirements.txt b/requirements.txt
index fe8a2c1..58a4641 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,5 +4,8 @@ flake8
 # previews.
 rst_include
 
+# the PySpice module for rendering FET bins plots
+PySpice
+
 # The Python API for the SkyWater PDK.
 -e scripts/python-skywater-pdk