diff --git a/i3pystatus/core/color.py b/i3pystatus/core/color.py
index c0326e4..6f36c37 100644
--- a/i3pystatus/core/color.py
+++ b/i3pystatus/core/color.py
@@ -2,6 +2,11 @@ from colour import Color
 
 
 class ColorRangeModule(object):
+    """
+    Class to dynamically generate and select colors.
+
+    Requires the PyPI package `colour`
+    """
 
     start_color = "#00FF00"
     end_color = 'red'
diff --git a/i3pystatus/cpu_usage_graph.py b/i3pystatus/cpu_usage_graph.py
index 818c111..3d5a907 100644
--- a/i3pystatus/cpu_usage_graph.py
+++ b/i3pystatus/cpu_usage_graph.py
@@ -8,6 +8,8 @@ class CpuUsageGraph(CpuUsage, ColorRangeModule):
      Shows CPU usage as a Unicode graph.
      The first output will be inacurate.
 
+     Depends on the PyPI colour module - https://pypi.python.org/pypi/colour/0.0.5
+
      Linux only
 
      Available formatters:
diff --git a/i3pystatus/network_graph.py b/i3pystatus/network_graph.py
index 1bc4747..a827763 100644
--- a/i3pystatus/network_graph.py
+++ b/i3pystatus/network_graph.py
@@ -10,6 +10,8 @@ class NetworkGraph(NetworkTraffic, ColorRangeModule):
 
     Linux only
 
+    Requires the PyPI packages `psutil` and `colour`.
+
     Available formatters:
 
     {kbs}               Float representing kb\s