diff --git a/modules/programs/khal-accounts.nix b/modules/programs/khal-accounts.nix
index cf04a65c..846e18fa 100644
--- a/modules/programs/khal-accounts.nix
+++ b/modules/programs/khal-accounts.nix
@@ -15,27 +15,11 @@ with lib;
     };
 
     color = mkOption {
-      type = types.nullOr (types.enum [
-        "black"
-        "white"
-        "brown"
-        "yellow"
-        "dark gray"
-        "dark green"
-        "dark blue"
-        "light gray"
-        "light green"
-        "light blue"
-        "dark magenta"
-        "dark cyan"
-        "dark red"
-        "light magenta"
-        "light cyan"
-        "light red"
-      ]);
+      type = types.nullOr types.str;
       default = null;
       description = ''
         Color in which events in this calendar are displayed.
+        For instance 'light green' or an RGB color '#ff0000'
       '';
       example = "light green";
     };
diff --git a/modules/programs/khal.nix b/modules/programs/khal.nix
index c8037e53..52e77963 100644
--- a/modules/programs/khal.nix
+++ b/modules/programs/khal.nix
@@ -45,10 +45,11 @@ let
         + (optionalString
           (value.khal.type == "birthdays" && value.khal ? thisCollection)
           value.khal.thisCollection)
-      }"
-    ] ++ optional (value.khal.readOnly) "readonly = True" ++ [
-      (toKeyValueIfDefined (getAttrs [ "type" "color" "priority" ] value.khal))
-    ] ++ [ "\n" ]);
+      }\n        "
+    ] ++ optional (value.khal.readOnly) "readonly = True"
+      ++ optional (value.khal.color != null) "color = '${value.khal.color}'"
+      ++ [ (toKeyValueIfDefined (getAttrs [ "type" "priority" ] value.khal)) ]
+      ++ [ "\n" ]);
 
   localeFormatOptions = let
     T = lib.types;
diff --git a/tests/modules/programs/khal/config.nix b/tests/modules/programs/khal/config.nix
index 50218e15..017a04ac 100644
--- a/tests/modules/programs/khal/config.nix
+++ b/tests/modules/programs/khal/config.nix
@@ -19,6 +19,7 @@
         khal = {
           enable = true;
           readOnly = true;
+          color = "#ff0000";
           type = "calendar";
         };
         local.type = "filesystem";
diff --git a/tests/modules/programs/khal/khal-config-expected b/tests/modules/programs/khal/khal-config-expected
index a4cf7a30..157d650b 100644
--- a/tests/modules/programs/khal/khal-config-expected
+++ b/tests/modules/programs/khal/khal-config-expected
@@ -1,7 +1,9 @@
 [calendars]
 [[test]]
 path = /home/hm-user/$XDG_CONFIG_HOME/cal/test/
+        
 readonly = True
+color = '#ff0000'
 priority=10
 type=calendar
 
@@ -9,6 +11,7 @@ type=calendar
 
 [[testcontacts-automaticallyCollected]]
 path = /home/hm-user/$XDG_CONFIG_HOME/card/testcontacts/automaticallyCollected
+        
 priority=10
 type=birthdays
 
@@ -16,6 +19,7 @@ type=birthdays
 
 [[testcontacts-default]]
 path = /home/hm-user/$XDG_CONFIG_HOME/card/testcontacts/default
+        
 priority=10
 type=birthdays
 
@@ -23,6 +27,7 @@ type=birthdays
 
 [[testcontactsNoCollections]]
 path = /home/hm-user/$XDG_CONFIG_HOME/card/testcontactsNoCollections/
+        
 priority=10
 type=birthdays