diff --git a/src/leetcode/merge-sorted-array/main.spec.ts b/src/leetcode/merge-sorted-array/main.spec.ts
new file mode 100644
index 0000000..dbe01a9
--- /dev/null
+++ b/src/leetcode/merge-sorted-array/main.spec.ts
@@ -0,0 +1,31 @@
+/**
+ * @copyright NHCarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+import { describe, it, expect } from "vitest";
+import { merge } from "./main.js";
+
+describe("merge", () => {
+  it("should merge the two arrays", () => {
+    const nums1 = [ 1, 2, 3, 0, 0, 0 ];
+    const nums2 = [ 2, 5, 6 ];
+    merge(nums1, nums2);
+    expect(nums1).toStrictEqual([ 1, 2, 2, 3, 5, 6 ]);
+  });
+
+  it("should merge the two arrays when the first array is empty", () => {
+    const nums1 = [ 0 ];
+    const nums2 = [ 1 ];
+    merge(nums1, nums2);
+    expect(nums1).toStrictEqual([ 1 ]);
+  });
+
+  it("should merge the two arrays when the second array is empty", () => {
+    const nums1 = [ 1, 2, 3, 0, 0, 0 ];
+    const nums2 = [ 2, 5, 6 ];
+    merge(nums1, nums2);
+    expect(nums1).toStrictEqual([ 1, 2, 2, 3, 5, 6 ]);
+  });
+});
diff --git a/src/leetcode/merge-sorted-array/main.ts b/src/leetcode/merge-sorted-array/main.ts
new file mode 100644
index 0000000..ce20767
--- /dev/null
+++ b/src/leetcode/merge-sorted-array/main.ts
@@ -0,0 +1,25 @@
+/**
+ * @copyright NHCarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+/**
+ * Mutates the first array to merge the second array into it.
+ * Returns nothing because LeetCode fucking wants you to mutate a param which is a terrible terrible idea.
+ * @param nums1 - The first array to merge into.
+ * @param nums2 - The second array to merge into the first.
+ * @see https://leetcode.com/problems/merge-sorted-array
+ */
+const merge = (nums1: Array<number>, nums2: Array<number>): void => {
+  while (nums2.length > 0) {
+    nums1.pop();
+    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion -- We assert it is not undefined immediately above this. But because we cannot use a variable, TypeScript doesn't narrow the type.
+    nums1.unshift(nums2.pop()!);
+  }
+  nums1.sort((a, b) => {
+    return a - b;
+  });
+};
+
+export { merge };