diff --git a/AI_MARKER b/AI_MARKER
new file mode 100644
index 0000000000..cde794874f
--- /dev/null
+++ b/AI_MARKER
@@ -0,0 +1 @@
+This contribution was prepared with AI assistance from OpenCode.
diff --git a/src/core/operations/ROT13BruteForce.mjs b/src/core/operations/ROT13BruteForce.mjs
index 7468ee1107..bbbff1d074 100644
--- a/src/core/operations/ROT13BruteForce.mjs
+++ b/src/core/operations/ROT13BruteForce.mjs
@@ -73,7 +73,7 @@ class ROT13BruteForce extends Operation {
         const cribLower = crib.toLowerCase();
         const lowerStart = "a".charCodeAt(0), upperStart = "A".charCodeAt(0), numStart = "0".charCodeAt(0);
         const result = [];
-        for (let amount = 1; amount < 26; amount++) {
+        for (let amount = 0; amount < 26; amount++) {
             const rotated = sample.slice();
             for (let i = 0; i < rotated.length; i++) {
                 if (rotateLower && lowerStart <= rotated[i] && rotated[i] < lowerStart + 26) {
diff --git a/tests/operations/tests/Rotate.mjs b/tests/operations/tests/Rotate.mjs
index a69e20fde6..f243cbd367 100644
--- a/tests/operations/tests/Rotate.mjs
+++ b/tests/operations/tests/Rotate.mjs
@@ -256,6 +256,28 @@ TestRegister.addTests([
             },
         ],
     },
+    {
+        name: "ROT13 Brute Force: includes pass-through",
+        input: "Abc123",
+        expectedMatch: /^Amount = {2}0: Abc123\nAmount = {2}1:/,
+        recipeConfig: [
+            {
+                op: "ROT13 Brute Force",
+                args: [true, true, true, 100, 0, true, ""]
+            },
+        ],
+    },
+    {
+        name: "ROT13 Brute Force: filters a pass-through sample",
+        input: "__Ab1__",
+        expectedOutput: "Ab1",
+        recipeConfig: [
+            {
+                op: "ROT13 Brute Force",
+                args: [true, true, true, 3, 2, false, "ab1"]
+            },
+        ],
+    },
     {
         name: "ROT47: nothing",
         input: "",