diff --git a/pyfritzhome/fritzhome.py b/pyfritzhome/fritzhome.py
index d57420b..35671c4 100644
--- a/pyfritzhome/fritzhome.py
+++ b/pyfritzhome/fritzhome.py
@@ -367,7 +367,7 @@ def set_color(self, ain, hsv, duration=0, mapped=True):
         if mapped:
             self._aha_request("setcolor", ain=ain, param=params)
         else:
-            # undocumented API method for free color selection
+            # available since Fritz!OS 7.39
             self._aha_request("setunmappedcolor", ain=ain, param=params)
 
     def get_color_temps(self, ain):