diff --git a/AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/AdventOfCode2023.FSharp.Lib.fsproj b/AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/AdventOfCode2023.FSharp.Lib.fsproj
index 7c5ca68..faa1752 100644
--- a/AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/AdventOfCode2023.FSharp.Lib.fsproj
+++ b/AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/AdventOfCode2023.FSharp.Lib.fsproj
@@ -22,6 +22,7 @@
     <Compile Include="Day9.fs"/>
     <Compile Include="Day10.fs" />
     <Compile Include="Day11.fs" />
+    <Compile Include="Day12.fs" />
   </ItemGroup>
 
 </Project>
diff --git a/AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Day12.fs b/AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Day12.fs
new file mode 100644
index 0000000..88ffe27
--- /dev/null
+++ b/AdventOfCode2023.FSharp/AdventOfCode2023.FSharp.Lib/Day12.fs
@@ -0,0 +1,14 @@
+namespace AdventOfCode2023
+
+[<RequireQualifiedAccess>]
+module Day12 =
+
+    let part1 (s : string) =
+        use mutable lines = StringSplitEnumerator.make '\n' s
+
+        -1
+
+    let part2 (s : string) =
+        use mutable lines = StringSplitEnumerator.make '\n' s
+
+        -1
diff --git a/AdventOfCode2023.FSharp/AdventOfCode2023.FSharp/Program.fs b/AdventOfCode2023.FSharp/AdventOfCode2023.FSharp/Program.fs
index 9f2d599..9e656f8 100644
--- a/AdventOfCode2023.FSharp/AdventOfCode2023.FSharp/Program.fs
+++ b/AdventOfCode2023.FSharp/AdventOfCode2023.FSharp/Program.fs
@@ -232,6 +232,25 @@ module Program =
             Console.WriteLine (part2.ToString ())
             Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
 
+        Console.WriteLine "=====Day 12====="
+
+        do
+            let input = Path.Combine (dir.FullName, "day12.txt") |> File.ReadAllText
+
+            sw.Restart ()
+            let part1 = Day12.part1 input
+            sw.Stop ()
+            Console.WriteLine (part1.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+            sw.Restart ()
+            let part2 = Day12.part2 input
+            sw.Stop ()
+            Console.WriteLine (part2.ToString ())
+            Console.Error.WriteLine ((1_000.0 * float sw.ElapsedTicks / float Stopwatch.Frequency).ToString () + "ms")
+
+        Console.WriteLine "=====Day 11====="
+
+
         endToEnd.Stop ()
 
         Console.Error.WriteLine (
diff --git a/AdventOfCode2023.FSharp/Test/Test.fsproj b/AdventOfCode2023.FSharp/Test/Test.fsproj
index 9fe6516..5af2d07 100644
--- a/AdventOfCode2023.FSharp/Test/Test.fsproj
+++ b/AdventOfCode2023.FSharp/Test/Test.fsproj
@@ -20,6 +20,7 @@
     <Compile Include="TestDay9.fs"/>
     <Compile Include="TestDay10.fs" />
     <Compile Include="TestDay11.fs" />
+    <Compile Include="TestDay12.fs" />
     <EmbeddedResource Include="samples\day1.txt"/>
     <EmbeddedResource Include="samples\day1part1.txt"/>
     <EmbeddedResource Include="samples\day2.txt"/>
@@ -34,6 +35,7 @@
     <EmbeddedResource Include="samples\day10part1.txt" />
     <EmbeddedResource Include="samples\day10.txt" />
     <EmbeddedResource Include="samples\day11.txt" />
+    <EmbeddedResource Include="samples\day12.txt" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/AdventOfCode2023.FSharp/Test/TestDay12.fs b/AdventOfCode2023.FSharp/Test/TestDay12.fs
new file mode 100644
index 0000000..75d84fb
--- /dev/null
+++ b/AdventOfCode2023.FSharp/Test/TestDay12.fs
@@ -0,0 +1,47 @@
+namespace AdventOfCode2023.Test
+
+open AdventOfCode2023
+open NUnit.Framework
+open FsUnitTyped
+open System.IO
+
+[<TestFixture>]
+module TestDay12 =
+
+    let sample = Assembly.getEmbeddedResource typeof<Dummy>.Assembly "day12.txt"
+
+    [<Test>]
+    let part1Sample () =
+        sample |> Day12.part1 |> shouldEqual 0
+
+    [<Test>]
+    let part2Sample () =
+        sample
+        |> Day12.part2
+        |> shouldEqual 0
+
+    [<Test>]
+    let part1Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day12.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day12.part1 s |> shouldEqual 0
+
+    [<Test>]
+    let part2Actual () =
+        let s =
+            try
+                File.ReadAllText (Path.Combine (__SOURCE_DIRECTORY__, "../../inputs/day12.txt"))
+            with
+            | :? DirectoryNotFoundException
+            | :? FileNotFoundException ->
+                Assert.Inconclusive ()
+                failwith "unreachable"
+
+        Day12.part2 s |> shouldEqual 0
diff --git a/AdventOfCode2023.FSharp/Test/samples/day12.txt b/AdventOfCode2023.FSharp/Test/samples/day12.txt
new file mode 100644
index 0000000..e69de29