diff --git a/Iceshrimp.Backend/Core/Helpers/LibMfm/Serialization/MfmSerializer.cs b/Iceshrimp.Backend/Core/Helpers/LibMfm/Serialization/MfmSerializer.cs
index c0bc7439..53900a72 100644
--- a/Iceshrimp.Backend/Core/Helpers/LibMfm/Serialization/MfmSerializer.cs
+++ b/Iceshrimp.Backend/Core/Helpers/LibMfm/Serialization/MfmSerializer.cs
@@ -56,9 +56,13 @@ public static class MfmSerializer
 				{
 					result.Append("$[");
 					result.Append(mfmFnNode.Name);
-					result.Append('.');
-					var args = mfmFnNode.Args.Select(p => p.Value != null ? $"{p.Key}={p.Value}" : $"{p.Key}");
-					result.Append(string.Join(',', args));
+					if (mfmFnNode.Args is { } args)
+					{
+						result.Append('.');
+						var str = args.Value.Select(p => p.Value != null ? $"{p.Key}={p.Value.Value}" : $"{p.Key}");
+						result.Append(string.Join(',', str));
+					}
+
 					result.Append(' ');
 					result.Append(Serialize(node.Children));
 					result.Append(']');
diff --git a/Iceshrimp.Parsing/Mfm.fs b/Iceshrimp.Parsing/Mfm.fs
index a6e52ad4..7c19b846 100644
--- a/Iceshrimp.Parsing/Mfm.fs
+++ b/Iceshrimp.Parsing/Mfm.fs
@@ -92,11 +92,10 @@ module MfmNodeTypes =
         member val Url = url
         member val Silent = silent
 
-    type MfmFnNode(args: Dictionary<string, string>, name, children) =
+    type MfmFnNode(name, args: IDictionary<string, string option> option, children) =
         inherit MfmInlineNode(children)
-        // (string, bool) args = (string, null as string?)
-        member val Args = args
         member val Name = name
+        member val Args = args
 
     type internal MfmCharNode(v: char) =
         inherit MfmInlineNode([])
@@ -163,6 +162,18 @@ module private MfmParser =
         | None -> user
         | Some v -> user + "@" + v
 
+    let fnArg =
+        many1Chars asciiLetter
+        .>>. opt (
+            pchar '='
+            >>. manyCharsTill anyChar (nextCharSatisfies <| fun p -> p = ',' || isWhitespace p)
+        )
+
+    let fnDict (input: (string * string option) list option) : IDictionary<string, string option> option =
+        match input with
+        | None -> None
+        | Some items -> items |> dict |> Some
+
     // References
     let node, nodeRef = createParserForwardedToRef ()
     let inlineNode, inlineNodeRef = createParserForwardedToRef ()
@@ -228,6 +239,13 @@ module private MfmParser =
         >>. manyCharsTill (satisfy isAsciiLetter <|> satisfy isDigit <|> anyOf "+-_") (skipChar ':')
         |>> fun e -> MfmEmojiCodeNode(e) :> MfmNode
 
+    let fnNode =
+        skipString "$[" >>. many1Chars asciiLower
+        .>>. opt (skipChar '.' >>. sepBy1 fnArg (skipChar ','))
+        .>> skipChar ' '
+        .>>. many1Till inlineNode (skipChar ']')
+        |>> fun ((n, o), c) -> MfmFnNode(n, fnDict o, aggregateTextInline c) :> MfmNode
+
     let plainNode =
         skipString "<plain>" >>. manyCharsTill anyChar (skipString "</plain>")
         |>> fun v -> MfmPlainNode(v) :> MfmNode
@@ -241,7 +259,8 @@ module private MfmParser =
         |>> fun c -> MfmCenterNode(aggregateTextInline c) :> MfmNode
 
     let mentionNode =
-        (previousCharSatisfiesNot isNotWhitespace <|> previousCharSatisfies (isAnyOf <| "()")) 
+        (previousCharSatisfiesNot isNotWhitespace
+         <|> previousCharSatisfies (isAnyOf <| "()"))
         >>. skipString "@"
         >>. many1Chars (
             satisfy isLetterOrNumber
@@ -337,9 +356,10 @@ module private MfmParser =
           linkNode
           mathNode
           emojiCodeNode
+          fnNode
           charNode ]
 
-    //TODO: still missing: FnNode, MfmSearchNode
+    //TODO: still missing: FnNode
 
     let blockNodeSeq =
         [ plainNode; centerNode; smallNode; codeBlockNode; mathBlockNode; quoteNode ]
diff --git a/Iceshrimp.Tests/Parsing/MfmTests.cs b/Iceshrimp.Tests/Parsing/MfmTests.cs
index e36163e4..ff26f0c0 100644
--- a/Iceshrimp.Tests/Parsing/MfmTests.cs
+++ b/Iceshrimp.Tests/Parsing/MfmTests.cs
@@ -1,6 +1,7 @@
 using Iceshrimp.Backend.Core.Helpers.LibMfm.Serialization;
 using Iceshrimp.Parsing;
 using Microsoft.FSharp.Collections;
+using Microsoft.FSharp.Core;
 using static Iceshrimp.Parsing.MfmNodeTypes;
 
 namespace Iceshrimp.Tests.Parsing;
@@ -38,9 +39,7 @@ public class MfmTests
 	{
 		List<MfmNode> expected =
 		[
-			new MfmInlineCodeNode("test"),
-			new MfmCodeBlockNode("test", null),
-			new MfmCodeBlockNode("test", "lang")
+			new MfmInlineCodeNode("test"), new MfmCodeBlockNode("test", null), new MfmCodeBlockNode("test", "lang")
 		];
 
 		var res = Mfm.parse("""
@@ -298,6 +297,54 @@ public class MfmTests
 		MfmSerializer.Serialize(res).Should().BeEquivalentTo(canonical);
 	}
 
+	[TestMethod]
+	public void TestFn()
+	{
+		const string input =
+			"test $[] $[test] $[test ] $[test test] $[test.a test] $[test.a=b test] $[test.a=b,c=e test] $[test.a,c=e test] $[test.a=b,c test]";
+
+		var some = FSharpOption<IDictionary<string, FSharpOption<string>>>.Some;
+		var none = FSharpOption<IDictionary<string, FSharpOption<string>>>.None;
+		var test = ListModule.OfSeq<MfmInlineNode>([new MfmTextNode("test")]);
+		
+		// @formatter:off
+		List<MfmNode> expected =
+		[
+			new MfmTextNode("test $[] $[test] $[test ] "),
+			new MfmFnNode("test",
+			              none,
+			              test),
+			new MfmTextNode(" "),
+			new MfmFnNode("test",
+			              some(new Dictionary<string, FSharpOption<string>>{ {"a", FSharpOption<string>.None} }),
+			              test),
+			new MfmTextNode(" "),
+			new MfmFnNode("test",
+			              some(new Dictionary<string, FSharpOption<string>>{ {"a", FSharpOption<string>.Some("b")} }),
+			              test),
+			new MfmTextNode(" "),
+			new MfmFnNode("test",
+			              some(new Dictionary<string, FSharpOption<string>>{ {"a", FSharpOption<string>.Some("b")}, {"c", FSharpOption<string>.Some("e")} }),
+			              test),
+			new MfmTextNode(" "),
+			new MfmFnNode("test",
+			              some(new Dictionary<string, FSharpOption<string>>{ {"a", FSharpOption<string>.None}, {"c", FSharpOption<string>.Some("e")} }),
+			              test),
+			new MfmTextNode(" "),
+			new MfmFnNode("test",
+			              some(new Dictionary<string, FSharpOption<string>>{ {"a", FSharpOption<string>.Some("b")}, {"c", FSharpOption<string>.None} }),
+			              test),
+		];
+		// @formatter:on
+
+		var res = Mfm.parse(input);
+
+		AssertionOptions.FormattingOptions.MaxDepth = 100;
+		res.ToList().Should().Equal(expected, MfmNodeEqual);
+
+		MfmSerializer.Serialize(res).Should().BeEquivalentTo(input);
+	}
+
 	[TestMethod]
 	public void Benchmark()
 	{
@@ -416,8 +463,13 @@ public class MfmTests
 			case MfmFnNode ax:
 			{
 				var bx = (MfmFnNode)b;
-				if (ax.Args != bx.Args) return false;
 				if (ax.Name != bx.Name) return false;
+				if ((ax.Args == null) != (bx.Args == null)) return false;
+				if (ax.Args == null || bx.Args == null) return true;
+				if (ax.Args.Value.Count != bx.Args.Value.Count) return false;
+				// ReSharper disable once UsageOfDefaultStructEquality
+				if (ax.Args.Value.Except(bx.Args.Value).Any()) return false;
+
 				break;
 			}
 		}