diff --git a/modules/misc/xdg-desktop-entries.nix b/modules/misc/xdg-desktop-entries.nix
index a810796f..7ec7fa56 100644
--- a/modules/misc/xdg-desktop-entries.nix
+++ b/modules/misc/xdg-desktop-entries.nix
@@ -107,7 +107,7 @@ let
       };
 
       settings = mkOption {
-        type = types.attrsOf types.string;
+        type = types.attrsOf types.str;
         description = ''
           Extra key-value pairs to add to the `[Desktop Entry]` section.
           This may override other values.
diff --git a/modules/programs/mu.nix b/modules/programs/mu.nix
index 835be361..04b0558e 100644
--- a/modules/programs/mu.nix
+++ b/modules/programs/mu.nix
@@ -29,6 +29,8 @@ in {
     programs.mu = {
       enable = mkEnableOption "mu, a maildir indexer and searcher";
 
+      package = mkPackageOption pkgs "mu" { };
+
       # No options/config file present for mu, and program author will not be
       # adding one soon. See https://github.com/djcb/mu/issues/882 for more
       # information about this.
@@ -42,7 +44,7 @@ in {
   };
 
   config = mkIf cfg.enable {
-    home.packages = [ pkgs.mu ];
+    home.packages = [ cfg.package ];
 
     home.activation.runMuInit = let
       maildirOption = genCmdMaildir config.accounts.email.maildirBasePath;
@@ -52,7 +54,9 @@ in {
       # In theory, mu is the only thing that creates that directory, and it is
       # only created during the initial index.
       if [[ ! -d "${dbLocation}" ]]; then
-        $DRY_RUN_CMD ${pkgs.mu}/bin/mu init ${maildirOption} ${myAddresses} $VERBOSE_ARG;
+        $DRY_RUN_CMD ${
+          getExe cfg.package
+        } init ${maildirOption} ${myAddresses} $VERBOSE_ARG;
       fi
     '';
   };
diff --git a/modules/programs/tmate.nix b/modules/programs/tmate.nix
index 025421bd..35547410 100644
--- a/modules/programs/tmate.nix
+++ b/modules/programs/tmate.nix
@@ -36,7 +36,7 @@ in {
       };
 
       dsaFingerprint = mkOption {
-        type = with types; nullOr string;
+        type = with types; nullOr str;
         default = null;
         example = literalExpression
           "SHA256:1111111111111111111111111111111111111111111";
@@ -44,7 +44,7 @@ in {
       };
 
       rsaFingerprint = mkOption {
-        type = with types; nullOr string;
+        type = with types; nullOr str;
         default = null;
         example = literalExpression
           "SHA256:1111111111111111111111111111111111111111111";
diff --git a/modules/services/kanshi.nix b/modules/services/kanshi.nix
index 3297d5fb..02fe8e3c 100644
--- a/modules/services/kanshi.nix
+++ b/modules/services/kanshi.nix
@@ -80,15 +80,28 @@ let
           Sets the output transform.
         '';
       };
+
+      adaptiveSync = mkOption {
+        type = types.nullOr types.bool;
+        default = null;
+        example = true;
+        description = ''
+          Enables or disables adaptive synchronization
+          (aka. Variable Refresh Rate).
+        '';
+      };
     };
   };
 
-  outputStr = { criteria, status, mode, position, scale, transform, ... }:
+  outputStr =
+    { criteria, status, mode, position, scale, transform, adaptiveSync, ... }:
     ''output "${criteria}"'' + optionalString (status != null) " ${status}"
     + optionalString (mode != null) " mode ${mode}"
     + optionalString (position != null) " position ${position}"
     + optionalString (scale != null) " scale ${toString scale}"
-    + optionalString (transform != null) " transform ${transform}";
+    + optionalString (transform != null) " transform ${transform}"
+    + optionalString (adaptiveSync != null)
+    " adaptive_sync ${if adaptiveSync then "on" else "off"}";
 
   profileModule = types.submodule {
     options = {
diff --git a/tests/modules/programs/mu/basic-configuration.nix b/tests/modules/programs/mu/basic-configuration.nix
index 4b315c2e..70b66fb9 100644
--- a/tests/modules/programs/mu/basic-configuration.nix
+++ b/tests/modules/programs/mu/basic-configuration.nix
@@ -12,7 +12,7 @@
 
   programs.mu.enable = true;
 
-  test.stubs.mu = { };
+  test.stubs.mu = { name = "mu"; };
 
   nmt.script = ''
     assertFileContains activate \