diff --git a/examples/qc_example.ipynb b/examples/qc_example.ipynb
index 7094db28f..5444441f2 100644
--- a/examples/qc_example.ipynb
+++ b/examples/qc_example.ipynb
@@ -417,7 +417,7 @@
     "window = 0.02 \n",
     "\n",
     "# Run the delta quality control test\n",
-    "results = qc.check_delta(results['cleaned_data'], expected_bound, window=window) \n",
+    "results = qc.check_delta(results['cleaned_data'], expected_bound, window) \n",
     "\n",
     "# Plot cleaned data\n",
     "results['cleaned_data'].plot(figsize=(15,5), ylim=(-60,60))\n",
diff --git a/requirements.txt b/requirements.txt
index 9af94213b..4f5d44baa 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,5 +3,5 @@ numpy
 scipy
 matplotlib
 requests
-pecos>=0.1.8
+pecos>=0.1.9
 fatpack
diff --git a/setup.py b/setup.py
index 15cb97b7d..a3a582166 100644
--- a/setup.py
+++ b/setup.py
@@ -22,7 +22,7 @@
                 'scipy',
                 'matplotlib', 
                 'requests', 
-                'pecos>=0.1.8',
+                'pecos>=0.1.9',
                 'fatpack',
                 'lxml',
                 'scikit-learn']