diff --git a/etc/requirements.txt b/etc/requirements.txt
index d0b11e38..278e4758 100644
--- a/etc/requirements.txt
+++ b/etc/requirements.txt
@@ -6,13 +6,14 @@ Logbook==0.7.0
 pytz==2014.3
 numpy==1.8.1
 
-# scipy is required for statsmodels
+# scipy and pandas are required for statsmodels,
+# statsmodels in turn is required for some pandas packages
 scipy==0.13.2
+pandas==0.12.0
 # Needed for parts of pandas.stats
 patsy==0.2.1
 statsmodels==0.5.0
 
-pandas==0.12.0
 python-dateutil==2.2
 six==1.6.1