diff --git a/.eslintrc.js b/.eslintrc.js
index 8d1675ad..fb7c1b3d 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -23,6 +23,10 @@ module.exports = {
     SpriteMesh: "readonly",
   },
 
+  rules: {
+    "no-unused-vars": ["error", { vars: "all", args: "after-used", varsIgnorePattern: "^_" }],
+  },
+
   overrides: [
     {
       files: ["./*.js", "./tools/**/*"],
diff --git a/src/hooks.js b/src/hooks.js
index b421bc70..62de64d7 100644
--- a/src/hooks.js
+++ b/src/hooks.js
@@ -1,6 +1,6 @@
 import { packageId } from "./constants.js";
 import { format } from "./logger.js";
-import { resetFlag } from "./utils.js";
+import { omit, resetFlag } from "./utils.js";
 
 export const registerHooks = function () {
   Hooks.on(`${packageId}.switchParticleEffect`, onSwitchParticleEffects);
@@ -16,17 +16,13 @@ async function onSwitchParticleEffects(parameters) {
   if (!canvas.scene) {
     return;
   }
-  const newEffect = { [parameters.name]: { type: parameters.type, options: parameters.options } };
 
-  let flags = (await canvas.scene.getFlag(packageId, "effects")) ?? {};
-  let effects = {};
+  const currentEffects = canvas.scene.getFlag(packageId, "effects") ?? {};
+  const shouldSwitchOff = parameters.name in currentEffects;
+  const effects = shouldSwitchOff
+    ? omit(currentEffects, parameters.name)
+    : { ...currentEffects, [parameters.name]: { type: parameters.type, options: parameters.options } };
 
-  if (foundry.utils.hasProperty(flags, parameters.name)) {
-    effects = flags;
-    delete effects[parameters.name];
-  } else {
-    effects = foundry.utils.mergeObject(flags, newEffect);
-  }
   if (Object.keys(effects).length == 0) {
     await canvas.scene.unsetFlag(packageId, "effects");
   } else {
diff --git a/src/utils.js b/src/utils.js
index 3ca41666..2cf797b2 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -28,3 +28,14 @@ export function resetFlag(document, key, value) {
 export function roundToDecimals(number, decimals) {
   return Number(Math.round(number + "e" + decimals) + "e-" + decimals);
 }
+
+/**
+ * Omit a specific key from an object.
+ * @param {object} object The object from which to omit
+ * @param {string|number|symbol} key The key to omit
+ * @returns {object} The object without the given key.
+ */
+export function omit(object, key) {
+  const { [key]: _omitted, ...rest } = object;
+  return rest;
+}