diff --git a/.github/github_workflows.ex b/.github/github_workflows.ex
index 4caaed8..c1a5cda 100644
--- a/.github/github_workflows.ex
+++ b/.github/github_workflows.ex
@@ -112,16 +112,16 @@ defmodule GithubWorkflows do
         "fail-fast": false,
         matrix: [
           versions: [
-            %{
+            [
               elixir: "1.11",
               otp: "21.3",
               "runner-image": "ubuntu-20.04"
-            },
-            %{
+            ],
+            [
               elixir: "1.16",
               otp: "26.2",
               "runner-image": "ubuntu-latest"
-            }
+            ]
           ]
         ]
       ],
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a7fa00f..f0463d9 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,9 +1,11 @@
 name: CI
+
 on:
-  pull_request: []
+  pull_request:
   push:
     branches:
       - main
+
 jobs:
   compile:
     name: Install deps and compile
@@ -12,11 +14,11 @@ jobs:
       fail-fast: false
       matrix:
         versions:
-          - otp: 21.3
-            elixir: 1.11
+          - elixir: 1.11
+            otp: 21.3
             runner-image: ubuntu-20.04
-          - otp: 26.2
-            elixir: 1.16
+          - elixir: 1.16
+            otp: 26.2
             runner-image: ubuntu-latest
     steps:
       - name: Checkout
@@ -28,9 +30,12 @@ jobs:
           otp-version: ${{ matrix.versions.otp }}
       - uses: actions/cache@v3
         with:
-          path: "_build\ndeps"
+          path: |
+            _build
+            deps
           key: mix-${{ matrix.versions.runner-image }}-${{ matrix.versions.otp }}-${{ matrix.versions.elixir }}-${{ github.sha }}
-          restore-keys: mix-${{ matrix.versions.runner-image }}-
+          restore-keys: |
+            mix-${{ matrix.versions.runner-image }}-
       - name: Install Elixir dependencies
         env:
           MIX_ENV: test
@@ -47,11 +52,11 @@ jobs:
       fail-fast: false
       matrix:
         versions:
-          - otp: 21.3
-            elixir: 1.11
+          - elixir: 1.11
+            otp: 21.3
             runner-image: ubuntu-20.04
-          - otp: 26.2
-            elixir: 1.16
+          - elixir: 1.16
+            otp: 26.2
             runner-image: ubuntu-latest
     steps:
       - name: Checkout
@@ -63,9 +68,12 @@ jobs:
           otp-version: ${{ matrix.versions.otp }}
       - uses: actions/cache@v3
         with:
-          path: "_build\ndeps"
+          path: |
+            _build
+            deps
           key: mix-${{ matrix.versions.runner-image }}-${{ matrix.versions.otp }}-${{ matrix.versions.elixir }}-${{ github.sha }}
-          restore-keys: mix-${{ matrix.versions.runner-image }}-
+          restore-keys: |
+            mix-${{ matrix.versions.runner-image }}-
       - name: Check code style
         env:
           MIX_ENV: test
@@ -78,11 +86,11 @@ jobs:
       fail-fast: false
       matrix:
         versions:
-          - otp: 21.3
-            elixir: 1.11
+          - elixir: 1.11
+            otp: 21.3
             runner-image: ubuntu-20.04
-          - otp: 26.2
-            elixir: 1.16
+          - elixir: 1.16
+            otp: 26.2
             runner-image: ubuntu-latest
     steps:
       - name: Checkout
@@ -94,9 +102,12 @@ jobs:
           otp-version: ${{ matrix.versions.otp }}
       - uses: actions/cache@v3
         with:
-          path: "_build\ndeps"
+          path: |
+            _build
+            deps
           key: mix-${{ matrix.versions.runner-image }}-${{ matrix.versions.otp }}-${{ matrix.versions.elixir }}-${{ github.sha }}
-          restore-keys: mix-${{ matrix.versions.runner-image }}-
+          restore-keys: |
+            mix-${{ matrix.versions.runner-image }}-
       - name: Check for vulnerable Mix dependencies
         env:
           MIX_ENV: test
@@ -109,11 +120,11 @@ jobs:
       fail-fast: false
       matrix:
         versions:
-          - otp: 21.3
-            elixir: 1.11
+          - elixir: 1.11
+            otp: 21.3
             runner-image: ubuntu-20.04
-          - otp: 26.2
-            elixir: 1.16
+          - elixir: 1.16
+            otp: 26.2
             runner-image: ubuntu-latest
     steps:
       - name: Checkout
@@ -125,15 +136,19 @@ jobs:
           otp-version: ${{ matrix.versions.otp }}
       - uses: actions/cache@v3
         with:
-          path: "_build\ndeps"
+          path: |
+            _build
+            deps
           key: mix-${{ matrix.versions.runner-image }}-${{ matrix.versions.otp }}-${{ matrix.versions.elixir }}-${{ github.sha }}
-          restore-keys: mix-${{ matrix.versions.runner-image }}-
+          restore-keys: |
+            mix-${{ matrix.versions.runner-image }}-
       - name: Restore PLT cache
         uses: actions/cache@v3
         with:
           path: priv/plts
           key: plt-${{ matrix.versions.runner-image }}-${{ matrix.versions.otp }}-${{ matrix.versions.elixir }}-${{ github.sha }}
-          restore-keys: plt-${{ matrix.versions.runner-image }}-
+          restore-keys: |
+            plt-${{ matrix.versions.runner-image }}-
       - name: Create PLTs
         env:
           MIX_ENV: test
@@ -150,11 +165,11 @@ jobs:
       fail-fast: false
       matrix:
         versions:
-          - otp: 21.3
-            elixir: 1.11
+          - elixir: 1.11
+            otp: 21.3
             runner-image: ubuntu-20.04
-          - otp: 26.2
-            elixir: 1.16
+          - elixir: 1.16
+            otp: 26.2
             runner-image: ubuntu-latest
     steps:
       - name: Checkout
@@ -166,9 +181,12 @@ jobs:
           otp-version: ${{ matrix.versions.otp }}
       - uses: actions/cache@v3
         with:
-          path: "_build\ndeps"
+          path: |
+            _build
+            deps
           key: mix-${{ matrix.versions.runner-image }}-${{ matrix.versions.otp }}-${{ matrix.versions.elixir }}-${{ github.sha }}
-          restore-keys: mix-${{ matrix.versions.runner-image }}-
+          restore-keys: |
+            mix-${{ matrix.versions.runner-image }}-
       - name: Check Elixir formatting
         env:
           MIX_ENV: test
@@ -181,11 +199,11 @@ jobs:
       fail-fast: false
       matrix:
         versions:
-          - otp: 21.3
-            elixir: 1.11
+          - elixir: 1.11
+            otp: 21.3
             runner-image: ubuntu-20.04
-          - otp: 26.2
-            elixir: 1.16
+          - elixir: 1.16
+            otp: 26.2
             runner-image: ubuntu-latest
     steps:
       - name: Checkout
@@ -197,9 +215,12 @@ jobs:
           otp-version: ${{ matrix.versions.otp }}
       - uses: actions/cache@v3
         with:
-          path: "_build\ndeps"
+          path: |
+            _build
+            deps
           key: mix-${{ matrix.versions.runner-image }}-${{ matrix.versions.otp }}-${{ matrix.versions.elixir }}-${{ github.sha }}
-          restore-keys: mix-${{ matrix.versions.runner-image }}-
+          restore-keys: |
+            mix-${{ matrix.versions.runner-image }}-
       - name: Check for retired Hex packages
         env:
           MIX_ENV: test
@@ -229,11 +250,11 @@ jobs:
       fail-fast: false
       matrix:
         versions:
-          - otp: 21.3
-            elixir: 1.11
+          - elixir: 1.11
+            otp: 21.3
             runner-image: ubuntu-20.04
-          - otp: 26.2
-            elixir: 1.16
+          - elixir: 1.16
+            otp: 26.2
             runner-image: ubuntu-latest
     steps:
       - name: Checkout
@@ -245,9 +266,12 @@ jobs:
           otp-version: ${{ matrix.versions.otp }}
       - uses: actions/cache@v3
         with:
-          path: "_build\ndeps"
+          path: |
+            _build
+            deps
           key: mix-${{ matrix.versions.runner-image }}-${{ matrix.versions.otp }}-${{ matrix.versions.elixir }}-${{ github.sha }}
-          restore-keys: mix-${{ matrix.versions.runner-image }}-
+          restore-keys: |
+            mix-${{ matrix.versions.runner-image }}-
       - name: Run tests
         env:
           MIX_ENV: test
@@ -262,11 +286,11 @@ jobs:
       fail-fast: false
       matrix:
         versions:
-          - otp: 21.3
-            elixir: 1.11
+          - elixir: 1.11
+            otp: 21.3
             runner-image: ubuntu-20.04
-          - otp: 26.2
-            elixir: 1.16
+          - elixir: 1.16
+            otp: 26.2
             runner-image: ubuntu-latest
     steps:
       - name: Checkout
@@ -278,9 +302,12 @@ jobs:
           otp-version: ${{ matrix.versions.otp }}
       - uses: actions/cache@v3
         with:
-          path: "_build\ndeps"
+          path: |
+            _build
+            deps
           key: mix-${{ matrix.versions.runner-image }}-${{ matrix.versions.otp }}-${{ matrix.versions.elixir }}-${{ github.sha }}
-          restore-keys: mix-${{ matrix.versions.runner-image }}-
+          restore-keys: |
+            mix-${{ matrix.versions.runner-image }}-
       - name: Check for unused Mix dependencies
         env:
           MIX_ENV: test
diff --git a/lib/github_workflows_generator.ex b/lib/github_workflows_generator.ex
index 2d18051..29ddd39 100644
--- a/lib/github_workflows_generator.ex
+++ b/lib/github_workflows_generator.ex
@@ -9,7 +9,12 @@ defmodule GithubWorkflowsGenerator do
          {:ok, workflows} <- get_workflows(source_path) do
       for {filename, data} <- workflows do
         path = Path.join(dir_path, filename)
-        yml = YmlEncoder.encode(data)
+
+        yml =
+          data
+          |> List.first()
+          |> YmlEncoder.encode()
+
         File.write!(path, yml)
       end
 
@@ -41,7 +46,7 @@ defmodule GithubWorkflowsGenerator do
       %{} ->
         {:error, "File #{source_path} does not contain any workflows."}
 
-      _ ->
+      _other ->
         {:error, "File #{source_path} does not have a valid structure."}
     end
   end
diff --git a/lib/github_workflows_generator/yml_encoder.ex b/lib/github_workflows_generator/yml_encoder.ex
index c217d4b..02fa3ba 100644
--- a/lib/github_workflows_generator/yml_encoder.ex
+++ b/lib/github_workflows_generator/yml_encoder.ex
@@ -4,18 +4,68 @@ defmodule GithubWorkflowsGenerator.YmlEncoder do
   @spec encode(term()) :: String.t()
   def encode(data) do
     data
-    |> Enum.at(0)
-    |> :fast_yaml.encode()
-    |> to_string()
-    # Trim trailing space
-    |> String.replace("\s\n", "\n")
-    # Avoid putting list element in new line after -
-    |> String.replace(~r/-\n\s+/, "-\s")
-    # Trim trailing newline inside strings
-    |> String.replace(~S(\n"), ~S("))
-    # Unquote strings
-    |> String.replace(~r<"([a-z0-9@_\-\.,: \{\}\$/\*\(\)'!=&\<\>~]+)">i, "\\1")
-    # Add newline to the EOF
+    |> to_yml()
+    |> String.trim()
     |> Kernel.<>("\n")
   end
+
+  defp to_yml(data, level \\ 0, indent? \\ false)
+
+  defp to_yml(data, level, indent?) when is_list(data) do
+    if Keyword.keyword?(data) do
+      handle_keyword_list(data, level, indent?)
+    else
+      Enum.map_join(
+        data,
+        "\n",
+        &(String.duplicate("  ", level) <> "- " <> to_yml(&1, level + 1, false))
+      )
+    end
+  end
+
+  defp to_yml(data, level, _indent?) do
+    cond do
+      !is_binary(data) ->
+        to_string(data)
+
+      String.contains?(data, "\n") ->
+        values =
+          data
+          |> String.split("\n", trim: true)
+          |> Enum.map_join("\n", &(String.duplicate("  ", level) <> &1))
+
+        "|\n#{values}"
+
+      true ->
+        data
+    end
+  end
+
+  defp handle_keyword_list(data, level, indent?) do
+    data
+    |> Enum.map_reduce(indent?, fn {key, value}, indent? ->
+      indentation =
+        if indent? do
+          String.duplicate("  ", level)
+        else
+          ""
+        end
+
+      {delimiter, string_value} =
+        case value do
+          [] ->
+            {"", ""}
+
+          value when is_list(value) ->
+            {"\n", to_yml(value, level + 1, true)}
+
+          value ->
+            {" ", to_yml(value, level + 1, false)}
+        end
+
+      {"#{indentation}#{key}:#{delimiter}#{string_value}", true}
+    end)
+    |> elem(0)
+    |> Enum.join(if(level == 0, do: "\n\n", else: "\n"))
+  end
 end
diff --git a/mix.exs b/mix.exs
index 0d6def6..6fc20ed 100644
--- a/mix.exs
+++ b/mix.exs
@@ -66,7 +66,6 @@ defmodule GithubWorkflowsGenerator.MixProject do
     [
       {:credo, "~> 1.7", only: [:test], runtime: false},
       {:dialyxir, "~> 1.4", only: [:test], runtime: false},
-      {:fast_yaml, "~> 1.0"},
       {:ex_doc, "~> 0.34", only: [:dev], runtime: false},
       {:excoveralls, "~> 0.18", only: [:test], runtime: false},
       {:mix_audit, "~> 1.0", only: [:test], runtime: false}
diff --git a/mix.lock b/mix.lock
index 5fd22b9..6c18a23 100644
--- a/mix.lock
+++ b/mix.lock
@@ -6,7 +6,6 @@
   "erlex": {:hex, :erlex, "0.2.6", "c7987d15e899c7a2f34f5420d2a2ea0d659682c06ac607572df55a43753aa12e", [:mix], [], "hexpm", "2ed2e25711feb44d52b17d2780eabf998452f6efda104877a3881c2f8c0c0c75"},
   "ex_doc": {:hex, :ex_doc, "0.34.0", "ab95e0775db3df71d30cf8d78728dd9261c355c81382bcd4cefdc74610bef13e", [:mix], [{:earmark_parser, "~> 1.4.39", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_c, ">= 0.1.0", [hex: :makeup_c, repo: "hexpm", optional: true]}, {:makeup_elixir, "~> 0.14 or ~> 1.0", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1 or ~> 1.0", [hex: :makeup_erlang, repo: "hexpm", optional: false]}, {:makeup_html, ">= 0.1.0", [hex: :makeup_html, repo: "hexpm", optional: true]}], "hexpm", "60734fb4c1353f270c3286df4a0d51e65a2c1d9fba66af3940847cc65a8066d7"},
   "excoveralls": {:hex, :excoveralls, "0.18.0", "b92497e69465dc51bc37a6422226ee690ab437e4c06877e836f1c18daeb35da9", [:mix], [{:castore, "~> 1.0", [hex: :castore, repo: "hexpm", optional: true]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "1109bb911f3cb583401760be49c02cbbd16aed66ea9509fc5479335d284da60b"},
-  "fast_yaml": {:hex, :fast_yaml, "1.0.36", "65413a34a570fd4e205a460ba602e4ee7a682f35c22d2e1c839025dbf515105c", [:rebar3], [{:p1_utils, "1.0.25", [hex: :p1_utils, repo: "hexpm", optional: false]}], "hexpm", "1abe8f758fc2a86b08edff80bbc687cfd41ebc1412cfec0ef4a0acfcd032052f"},
   "file_system": {:hex, :file_system, "1.0.0", "b689cc7dcee665f774de94b5a832e578bd7963c8e637ef940cd44327db7de2cd", [:mix], [], "hexpm", "6752092d66aec5a10e662aefeed8ddb9531d79db0bc145bb8c40325ca1d8536d"},
   "jason": {:hex, :jason, "1.4.1", "af1504e35f629ddcdd6addb3513c3853991f694921b1b9368b0bd32beb9f1b63", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "fbb01ecdfd565b56261302f7e1fcc27c4fb8f32d56eab74db621fc154604a7a1"},
   "makeup": {:hex, :makeup, "1.1.2", "9ba8837913bdf757787e71c1581c21f9d2455f4dd04cfca785c70bbfff1a76a3", [:mix], [{:nimble_parsec, "~> 1.2.2 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "cce1566b81fbcbd21eca8ffe808f33b221f9eee2cbc7a1706fc3da9ff18e6cac"},
@@ -14,7 +13,6 @@
   "makeup_erlang": {:hex, :makeup_erlang, "1.0.0", "6f0eff9c9c489f26b69b61440bf1b238d95badae49adac77973cbacae87e3c2e", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "ea7a9307de9d1548d2a72d299058d1fd2339e3d398560a0e46c27dab4891e4d2"},
   "mix_audit": {:hex, :mix_audit, "1.0.1", "9dd114408961b8db214f42fee40b2f632ecd7e4fd29500403068c82c77db8361", [:make, :mix], [{:jason, "~> 1.1", [hex: :jason, repo: "hexpm", optional: false]}, {:yaml_elixir, "~> 2.8.0", [hex: :yaml_elixir, repo: "hexpm", optional: false]}], "hexpm", "65066bb7757078aa49faaa2f7c1e2d52f56ff6fe6cff01723dbaf5be2a75771b"},
   "nimble_parsec": {:hex, :nimble_parsec, "1.4.0", "51f9b613ea62cfa97b25ccc2c1b4216e81df970acd8e16e8d1bdc58fef21370d", [:mix], [], "hexpm", "9c565862810fb383e9838c1dd2d7d2c437b3d13b267414ba6af33e50d2d1cf28"},
-  "p1_utils": {:hex, :p1_utils, "1.0.25", "2d39b5015a567bbd2cc7033eeb93a7c60d8c84efe1ef69a3473faa07fa268187", [:rebar3], [], "hexpm", "9219214428f2c6e5d3187ff8eb9a8783695c2427420be9a259840e07ada32847"},
   "yamerl": {:hex, :yamerl, "0.10.0", "4ff81fee2f1f6a46f1700c0d880b24d193ddb74bd14ef42cb0bcf46e81ef2f8e", [:rebar3], [], "hexpm", "346adb2963f1051dc837a2364e4acf6eb7d80097c0f53cbdc3046ec8ec4b4e6e"},
   "yaml_elixir": {:hex, :yaml_elixir, "2.8.0", "c7ff0034daf57279c2ce902788ce6fdb2445532eb4317e8df4b044209fae6832", [:mix], [{:yamerl, "~> 0.8", [hex: :yamerl, repo: "hexpm", optional: false]}], "hexpm", "4b674bd881e373d1ac6a790c64b2ecb69d1fd612c2af3b22de1619c15473830b"},
 }
diff --git a/test/github_workflows_generator/yml_encoder_test.exs b/test/github_workflows_generator/yml_encoder_test.exs
new file mode 100644
index 0000000..11a216f
--- /dev/null
+++ b/test/github_workflows_generator/yml_encoder_test.exs
@@ -0,0 +1,92 @@
+defmodule GithubWorkflowsGenerator.YmlEncoderTest do
+  use ExUnit.Case, async: true
+
+  alias GithubWorkflowsGenerator.YmlEncoder
+
+  describe "encode/1" do
+    test "encodes a list" do
+      assert YmlEncoder.encode([:pull_request, :push]) == """
+             - pull_request
+             - push
+             """
+    end
+
+    test "encodes a multiline string" do
+      assert YmlEncoder.encode(path: "_build\ndeps") == """
+             path: |
+               _build
+               deps
+             """
+    end
+
+    test "encodes a list of lists" do
+      assert YmlEncoder.encode(on: [pull_request: [], push: [branches: ["main"]]]) == """
+             on:
+               pull_request:
+               push:
+                 branches:
+                   - main
+             """
+    end
+
+    test "encodes a complex data structure" do
+      assert YmlEncoder.encode(
+               on: [
+                 schedule: [
+                   [cron: "30 5 * * 1,3"],
+                   [cron: "30 5 * * 2,4"]
+                 ]
+               ],
+               jobs: [
+                 test_schedule: [
+                   "runs-on": "ubuntu-latest",
+                   steps: [
+                     [
+                       name: "Not on Monday or Wednesday",
+                       if: "github.event.schedule != '30 5 * * 1,3'",
+                       run: "echo \"This step will be skipped on Monday and Wednesday\""
+                     ],
+                     [
+                       name: "Every time",
+                       run: "echo \"This step will always run\""
+                     ],
+                     [
+                       uses: "actions/cache@v3",
+                       with: [
+                         path: "_build\ndeps",
+                         key:
+                           "mix-${{ matrix.versions.runner-image }}-${{ matrix.versions.otp }}-${{ matrix.versions.elixir }}-${{ github.sha }}",
+                         "restore-keys": "\nmix-${{ matrix.versions.runner-image }}"
+                       ]
+                     ]
+                   ]
+                 ]
+               ]
+             ) ==
+               """
+               on:
+                 schedule:
+                   - cron: 30 5 * * 1,3
+                   - cron: 30 5 * * 2,4
+
+               jobs:
+                 test_schedule:
+                   runs-on: ubuntu-latest
+                   steps:
+                     - name: Not on Monday or Wednesday
+                       if: github.event.schedule != '30 5 * * 1,3'
+                       run: echo "This step will be skipped on Monday and Wednesday"
+                     - name: Every time
+                       run: echo "This step will always run"
+                     - uses: actions/cache@v3
+                       with:
+                         path: |
+                           _build
+                           deps
+                         key: mix-${{ matrix.versions.runner-image }}-${{ matrix.versions.otp }}-${{ matrix.versions.elixir }}-${{ github.sha }}
+                         restore-keys: |
+                           mix-${{ matrix.versions.runner-image }}
+               """
+    end
+  end
+end