diff --git a/PyFVCOM/utilities/time.py b/PyFVCOM/utilities/time.py
index 675fe61f..331d6e96 100644
--- a/PyFVCOM/utilities/time.py
+++ b/PyFVCOM/utilities/time.py
@@ -170,8 +170,10 @@ def date_range(start_date, end_date, inc=1):
 
     """
 
-    start_seconds = int(start_date.replace(tzinfo=pytz.UTC).strftime('%s'))
-    end_seconds = int(end_date.replace(tzinfo=pytz.UTC).strftime('%s'))
+    # start_seconds = int(start_date.replace(tzinfo=pytz.UTC).strftime('%s'))
+    start_seconds = int(start_date.replace(tzinfo=pytz.UTC).timestamp())
+    # end_seconds = int(end_date.replace(tzinfo=pytz.UTC).strftime('%s'))
+    end_seconds = int(end_date.replace(tzinfo=pytz.UTC).timestamp())
 
     inc *= 86400  # seconds
     dates = np.arange(start_seconds, end_seconds, inc)
diff --git a/examples/pyfvcom_preprocessing_example.ipynb b/examples/pyfvcom_preprocessing_example.ipynb
index d89da325..982187d3 100644
--- a/examples/pyfvcom_preprocessing_example.ipynb
+++ b/examples/pyfvcom_preprocessing_example.ipynb
@@ -90,7 +90,7 @@
    "outputs": [],
    "source": [
     "# Make a vertical grid with 21 uniform levels\n",
-    "model.sigma.type = 'uniform'\n",
+    "model.sigma.type = 'UNIFORM'\n",
     "model.dims.levels = 21"
    ]
   },
diff --git a/examples/pyfvcom_preprocessing_example.py b/examples/pyfvcom_preprocessing_example.py
index d2792d8e..4b8e8407 100644
--- a/examples/pyfvcom_preprocessing_example.py
+++ b/examples/pyfvcom_preprocessing_example.py
@@ -57,7 +57,7 @@
 # In[6]:
 
 # Make a vertical grid with 21 uniform levels
-model.sigma.type = 'uniform'
+model.sigma.type = 'UNIFORM'
 model.dims.levels = 21