diff --git a/home/.config/niri/config.kdl b/home/.config/niri/config.kdl
index d1bb2b8..21a48db 100644
--- a/home/.config/niri/config.kdl
+++ b/home/.config/niri/config.kdl
@@ -337,6 +337,7 @@ screenshot-path "~/Pictures/Screenshots/Screenshot from %Y-%m-%d %H-%M-%S.png"
 
 spawn-at-startup "dms" "run"
 spawn-at-startup "kdeconnect-indicator"
+spawn-at-startup "~/rep/flocon/home/bin/monitor-dark-mode.sh"
 
 spawn-at-startup "xwayland-satellite"
 environment {
diff --git a/home/bin/monitor-dark-mode.sh b/home/bin/monitor-dark-mode.sh
new file mode 100755
index 0000000..e8cdaf4
--- /dev/null
+++ b/home/bin/monitor-dark-mode.sh
@@ -0,0 +1,4 @@
+#!/usr/bin/env sh
+
+gsettings monitor org.gnome.desktop.interface color-scheme \
+  | xargs -L1 "${HOME}/rep/flocon/home/bin/switch-helix-theme.sh"
diff --git a/home/bin/switch-helix-theme.sh b/home/bin/switch-helix-theme.sh
new file mode 100755
index 0000000..f11f803
--- /dev/null
+++ b/home/bin/switch-helix-theme.sh
@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+
+set -euox pipefail
+
+HELIX_CONFIG_PATH=$(readlink -f "${HOME}/.config/helix/config.toml")
+HELIX_THEME_LIGHT="zed_onelight"
+HELIX_THEME_DARK="kanagawa"
+
+if [[ "$2" == "prefer-dark" ]]; then
+  sed -i "s/^theme .*/theme = \"$HELIX_THEME_DARK\"/" "$HELIX_CONFIG_PATH"
+else
+  sed -i "s/^theme .*/theme = \"$HELIX_THEME_LIGHT\"/" "$HELIX_CONFIG_PATH"
+fi
+
+pkill -USR1 hx || true