diff --git a/docs/source/configuration/common.rst b/docs/source/configuration/common.rst
index a99156c..3548000 100644
--- a/docs/source/configuration/common.rst
+++ b/docs/source/configuration/common.rst
@@ -12,7 +12,7 @@ Attributes:
     * | **val:** float
       |   The value of the minimal wavelength.
     * | **val_unit:** str, *optional* = "m"
-      |   The unit of the minimal wavelength. This has to be one of [``m``, ``cm``, ``mm``, ``um``, ``nm``, ``pm``]. The default is ``m``.
+      |   The unit of the minimal wavelength. This has to be one of [``m``, ``cm``, ``mm``, ``um``, ``nm``, ``pm``, ``Hz``, ``kHZ``, ``MHz``, ``GHz``, ``THz``]. The default is ``m``.
 
 wl_max
 ------
@@ -26,7 +26,7 @@ Attributes:
     * | **val:** float
       |   The value of the maximal wavelength.
     * | **val_unit:** str, *optional* = "m"
-      |   The unit of the maximal wavelength. This has to be one of [``m``, ``cm``, ``mm``, ``um``, ``nm``, ``pm``]. The default is ``m``.
+      |   The unit of the maximal wavelength. This has to be one of [``m``, ``cm``, ``mm``, ``um``, ``nm``, ``pm``, ``Hz``, ``kHZ``, ``MHz``, ``GHz``, ``THz``]. The default is ``m``.
 
 .. _wl_delta:
 
@@ -42,7 +42,7 @@ Attributes:
     * | **val:** float
       |   The value of the wavelength grid size.
     * | **val_unit:** str, *optional* = "m"
-      |   The unit of the wavelength grid size. This has to be one of [``m``, ``cm``, ``mm``, ``um``, ``nm``, ``pm``]. The default is ``m``.
+      |   The unit of the wavelength grid size. This has to be one of [``m``, ``cm``, ``mm``, ``um``, ``nm``, ``pm``, ``Hz``, ``kHZ``, ``MHz``, ``GHz``, ``THz``]. The default is ``m``.
 
 .. _res:
 
diff --git a/docs/source/configuration/sensor.rst b/docs/source/configuration/sensor.rst
index e498564..0252a9a 100644
--- a/docs/source/configuration/sensor.rst
+++ b/docs/source/configuration/sensor.rst
@@ -310,7 +310,7 @@ Attributes:
     * | **val:** float
       |   The wavelength of the observed line.
     * | **val_unit:** str, *optional* = "m"
-      |   The unit of the observed line wavelength. This has to be on of [``nm``, ``um``, ``mm``, ``cm``, ``m``].
+      |   The unit of the observed line wavelength. This has to be on of [``nm``, ``um``, ``mm``, ``cm``, ``m``, ``Hz``, ``kHZ``, ``MHz``, ``GHz``, ``THz``].
 
 kappa
 ^^^^^
diff --git a/esbo_etc/classes/Entry.py b/esbo_etc/classes/Entry.py
index f14673f..339043a 100644
--- a/esbo_etc/classes/Entry.py
+++ b/esbo_etc/classes/Entry.py
@@ -83,7 +83,11 @@ class Entry(object):
                 return "Expected parameter '" + name + "' with unit '" + unit.to_string() + "' but got no unit."
         if not attr.unit.is_equivalent(unit):
             if unit == u.K and attr.unit == u.Celsius:
-                setattr(self, name, attr.to(u.K, equivalencies=u.temperature()))
+                setattr(self, name, attr.to(unit, equivalencies=u.temperature()))
+                setattr(self, name + '_unit', unit.to_string())
+            elif unit.is_equivalent(u.m) and attr.unit.is_equivalent(u.Hz):
+                setattr(self, name, attr.to(unit, equivalencies=u.spectral()))
+                setattr(self, name + '_unit', unit.to_string())
             else:
                 return "Expected parameter '" + name + "' with unit equivalent to '" + unit.to_string() + \
                    "' but got unit '" + attr.unit.to_string() + "'."