diff --git a/nw/core/index.py b/nw/core/index.py
index 456b415c..632375a7 100644
--- a/nw/core/index.py
+++ b/nw/core/index.py
@@ -41,7 +41,7 @@ logger = logging.getLogger(__name__)
 
 class NWIndex():
 
-    VALID_KEYS = set([
+    VALID_KEYS = {
         nwKeyWords.TAG_KEY,
         nwKeyWords.PLOT_KEY,
         nwKeyWords.POV_KEY,
@@ -51,7 +51,7 @@ class NWIndex():
         nwKeyWords.OBJECT_KEY,
         nwKeyWords.ENTITY_KEY,
         nwKeyWords.CUSTOM_KEY
-    ])
+    }
     TAG_CLASS  = {
         nwKeyWords.CHAR_KEY   : nwItemClass.CHARACTER,
         nwKeyWords.POV_KEY    : nwItemClass.CHARACTER,
diff --git a/nw/core/options.py b/nw/core/options.py
index abab6a65..25bf1fb4 100644
--- a/nw/core/options.py
+++ b/nw/core/options.py
@@ -45,7 +45,7 @@ class OptionState():
 
         self.theState = {}
         self.validMap = {
-            "GuiSession": set([
+            "GuiSession": {
                 "widthCol0",
                 "widthCol1",
                 "widthCol2",
@@ -53,11 +53,11 @@ class OptionState():
                 "sortOrder",
                 "hideZeros",
                 "hideNegative",
-            ]),
-            "GuiDocSplit": set([
+            },
+            "GuiDocSplit": {
                 "spLevel",
-            ]),
-            "GuiBuildNovel": set([
+            },
+            "GuiBuildNovel": {
                 "winWidth",
                 "winHeight",
                 "addNovel",
@@ -72,12 +72,12 @@ class OptionState():
                 "incComments",
                 "incKeywords",
                 "incBodyText",
-            ]),
-            "GuiOutline": set([
+            },
+            "GuiOutline": {
                 "headerOrder",
                 "columnWidth",
                 "columnHidden",
-            ]),
+            },
         }
 
         return