diff --git a/frontend/__tests__/test/funbox/funbox-validation.spec.ts b/frontend/__tests__/test/funbox/funbox-validation.spec.ts
new file mode 100644
index 000000000..7a570c20a
--- /dev/null
+++ b/frontend/__tests__/test/funbox/funbox-validation.spec.ts
@@ -0,0 +1,74 @@
+import { canSetConfigWithCurrentFunboxes } from "../../../src/ts/test/funbox/funbox-validation";
+
+import * as Notifications from "../../../src/ts/elements/notifications";
+describe("funbox-validation", () => {
+  describe("canSetConfigWithCurrentFunboxes", () => {
+    const addNotificationMock = vi.spyOn(Notifications, "add");
+    afterEach(() => {
+      addNotificationMock.mockReset();
+    });
+
+    const testCases = [
+      //checks for frontendForcedConfig
+      {
+        key: "mode",
+        value: "zen",
+        funbox: ["memory"],
+        error: "You can't set mode to zen with currently active funboxes.",
+      },
+      { key: "mode", value: "words", funbox: ["memory"] }, //ok
+
+      //checks for zen mode
+      ...[
+        "58008", //getWord
+        "wikipedia", //pullSection
+        "morse", //alterText
+        "polyglot", //withWords
+        "rAnDoMcAsE", //changesCapitalisation
+        "nospace", //nospace
+        "plus_one", //toPush:
+        "read_ahead_easy", //changesWordVisibility
+        "tts", //speaks
+        "layout_mirror", //changesLayout
+        "zipf", //changesWordsFrequency
+      ].map((funbox) => ({
+        key: "mode",
+        value: "zen",
+        funbox: [funbox],
+        error: "You can't set mode to zen with currently active funboxes.",
+      })),
+      { key: "mode", value: "zen", funbox: ["mirror"] }, //ok
+      { key: "mode", value: "zen", funbox: ["space_balls"] }, //no frontendFunctions
+
+      //checks for words and custom
+      ...["quote", "custom"].flatMap((value) =>
+        [
+          "58008", //getWord
+          "wikipedia", //pullSection
+          "polyglot", //withWords
+          "zipf", //changesWordsFrequency
+        ].map((funbox) => ({
+          key: "mode",
+          value,
+          funbox: [funbox],
+          error: `You can't set mode to ${value} with currently active funboxes.`,
+        }))
+      ),
+      { key: "mode", value: "quote", funbox: ["space_balls"] }, //no frontendFunctions
+    ];
+    it.for(testCases)(
+      `check $funbox with $key=$value`,
+      ({ key, value, funbox, error }) => {
+        expect(
+          canSetConfigWithCurrentFunboxes(key, value, funbox.join("#"))
+        ).toBe(error === undefined);
+
+        if (error !== undefined) {
+          expect(addNotificationMock).toHaveBeenCalledWith(error, 0, {
+            duration: 5,
+          });
+        }
+      }
+    );
+  });
+});
diff --git a/frontend/src/ts/test/funbox/funbox-validation.ts b/frontend/src/ts/test/funbox/funbox-validation.ts
index bd0cb8ba7..6004526ff 100644
--- a/frontend/src/ts/test/funbox/funbox-validation.ts
+++ b/frontend/src/ts/test/funbox/funbox-validation.ts
@@ -86,18 +86,20 @@ export function canSetConfigWithCurrentFunboxes(
     if (value === "zen") {
       fb = fb.concat(
         getFunboxesFromString(funbox).filter((f) => {
+          const funcs = f.frontendFunctions ?? [];
+          const props = f.properties ?? [];
           return (
-            f.frontendFunctions?.includes("getWord") ||
-            f.frontendFunctions?.includes("pullSection") ||
-            f.frontendFunctions?.includes("alterText") ||
-            f.frontendFunctions?.includes("withWords") ||
-            f.properties?.includes("changesCapitalisation") ||
-            f.properties?.includes("nospace") ||
-            f.properties?.some((fp) => fp.startsWith("toPush:")) ||
-            f.properties?.includes("changesWordsVisibility") ||
-            f.properties?.includes("speaks") ||
-            f.properties?.includes("changesLayout") ||
-            f.properties?.includes("changesWordsFrequency")
+            funcs.includes("getWord") ||
+            funcs.includes("pullSection") ||
+            funcs.includes("alterText") ||
+            funcs.includes("withWords") ||
+            props.includes("changesCapitalisation") ||
+            props.includes("nospace") ||
+            props.some((fp) => fp.startsWith("toPush:")) ||
+            props.includes("changesWordsVisibility") ||
+            props.includes("speaks") ||
+            props.includes("changesLayout") ||
+            props.includes("changesWordsFrequency")
           );
         })
       );
@@ -105,11 +107,13 @@ export function canSetConfigWithCurrentFunboxes(
     if (value === "quote" || value === "custom") {
       fb = fb.concat(
         getFunboxesFromString(funbox).filter((f) => {
+          const funcs = f.frontendFunctions ?? [];
+          const props = f.properties ?? [];
           return (
-            f.frontendFunctions?.includes("getWord") ||
-            f.frontendFunctions?.includes("pullSection") ||
-            f.frontendFunctions?.includes("withWords") ||
-            f.properties?.includes("changesWordsFrequency")
+            funcs.includes("getWord") ||
+            funcs.includes("pullSection") ||
+            funcs.includes("withWords") ||
+            props.includes("changesWordsFrequency")
           );
         })
       );