diff --git a/src/core/file-handling/formats/json.js b/src/core/file-handling/formats/json.js
index 7f5ccd2..2d69100 100644
--- a/src/core/file-handling/formats/json.js
+++ b/src/core/file-handling/formats/json.js
@@ -1,6 +1,6 @@
 import { ResultMatcher } from "../../utils/resultMatcher.js";
 import { LoadingException } from "../exception.js";
-import { flattenTree } from "../utils.js";
+import { flattenTree, setPathOnTree } from "../utils.js";
 
 /** @type {import("../types.js").FormatHandler} */
 export const JsonHandler = {
@@ -28,29 +28,7 @@ export const JsonHandler = {
     const obj = JSON.parse(oldJSON);
 
     const path = key.split(".");
-
-    /**
-     * @param {any} tree
-     * @param {string[]} path
-     * @param {string} value
-     * @returns
-     */
-    function setOnTree(tree, path, value) {
-      //Split the path into the current level and the rest of the path
-      const [current, ...rest] = path;
-      if (!current)
-        throw new Error("There must be at least one level in the path");
-
-      if (rest.length === 0) {
-        tree[current] = value;
-        return;
-      }
-
-      if (!tree[current]) tree[current] = {};
-      setOnTree(tree[current], rest, value);
-    }
-
-    setOnTree(obj, path, value);
+    setPathOnTree(obj, path, value);
 
     const newJSON = JSON.stringify(obj);
     return newJSON;
diff --git a/src/core/file-handling/formats/yaml.js b/src/core/file-handling/formats/yaml.js
index afe63c7..4fd6c12 100644
--- a/src/core/file-handling/formats/yaml.js
+++ b/src/core/file-handling/formats/yaml.js
@@ -1,5 +1,5 @@
-import { load as loadYaml, YAMLException } from "js-yaml";
-import { flattenTree } from "../utils.js";
+import { dump, load as loadYaml, YAMLException } from "js-yaml";
+import { flattenTree, setPathOnTree } from "../utils.js";
 import { LoadingException } from "../exception.js";
 import { ResultMatcher } from "../../utils/resultMatcher.js";
 
@@ -7,20 +7,45 @@ import { ResultMatcher } from "../../utils/resultMatcher.js";
 export const YamlHandler = {
   fileExtensions: ["yaml", "yml"],
   load: (filePath, content) => {
-    /** @param {YAMLException} e */
-    const raiseLoadingException = (e) => {
-      throw new LoadingException(
-        `Could not parse YAML file ${filePath}: ${e.message}`,
-        { cause: e },
-      );
-    };
-
-    return new ResultMatcher(loadYaml)
-      .ok(flattenTree)
-      .catch(YAMLException, raiseLoadingException)
-      .run(content, { filename: filePath });
+    const tree = parseAsTree(content, filePath);
+    return new ResultMatcher(flattenTree)
+      .catchAll((e) => raiseLoadingException(e, filePath))
+      .run(tree);
   },
-  setPath() {
-    throw new Error("Not implemented");
+  setPath(oldYaml, key, value) {
+    const tree = parseAsTree(oldYaml);
+
+    const path = key.split(".");
+    setPathOnTree(tree, path, value);
+
+    const newYaml = dump(tree);
+    return newYaml;
   },
 };
+
+/**
+ * @param {string} content
+ * @param {string|undefined} filePath
+ * @return {unknown}
+ */
+function parseAsTree(content, filePath = undefined) {
+  return new ResultMatcher(loadYaml)
+    .ok((res) => {
+      if (typeof res !== "object") return {};
+      return res;
+    })
+    .catch(YAMLException, (e) => raiseLoadingException(e, filePath))
+    .run(content, { filename: filePath });
+}
+
+/**
+ * @param {unknown} e
+ * @param {string | undefined} filePath
+ */
+const raiseLoadingException = (e, filePath = undefined) => {
+  const msg =
+    e instanceof Error
+      ? `Could not parse YAML file ${filePath ?? ""}: ${e.message}`
+      : `Could not parse YAML file ${filePath ?? ""}`;
+  throw new LoadingException(msg, { cause: e });
+};
diff --git a/src/core/file-handling/formats/yaml.test.js b/src/core/file-handling/formats/yaml.test.js
new file mode 100644
index 0000000..7762dd1
--- /dev/null
+++ b/src/core/file-handling/formats/yaml.test.js
@@ -0,0 +1,21 @@
+import { describe, expect, it } from "vitest";
+import { LoadingException } from "../exception";
+import { YamlHandler } from "./yaml";
+
+describe("YamlHandler", () => {
+  it("parses an empty file as an empty dictionary", () => {
+    const result = YamlHandler.load("test.yaml", "");
+    expect(result).toEqual(new Map());
+  });
+
+  it("sets a path on an empty file", () => {
+    const newYaml = YamlHandler.setPath("", "key1.key2", "value");
+    expect(newYaml).toEqual("key1:\n  key2: value\n");
+  });
+
+  it("sets a path on an existing file", () => {
+    const oldYaml = "key1:\n  key2: value\n";
+    const newYaml = YamlHandler.setPath(oldYaml, "key1.key3", "value");
+    expect(newYaml).toEqual("key1:\n  key2: value\n  key3: value\n");
+  });
+});
diff --git a/src/core/file-handling/utils.js b/src/core/file-handling/utils.js
index 5b6838e..4a0bfda 100644
--- a/src/core/file-handling/utils.js
+++ b/src/core/file-handling/utils.js
@@ -38,3 +38,26 @@ export function flattenTree(tree) {
     throw new Error("Invalid tree");
   }
 }
+
+/**
+ * Modifies a tree so that the given path has the given value.
+ * Will create intermediate levels as needed.
+ *
+ * @param {any} tree
+ * @param {string[]} path
+ * @param {string} value
+ * @returns
+ */
+export function setPathOnTree(tree, path, value) {
+  //Split the path into the current level and the rest of the path
+  const [current, ...rest] = path;
+  if (!current) throw new Error("There must be at least one level in the path");
+
+  if (rest.length === 0) {
+    tree[current] = value;
+    return;
+  }
+
+  if (!tree[current]) tree[current] = {};
+  setPathOnTree(tree[current], rest, value);
+}