diff --git a/.github/workflows/develop.yml b/.github/workflows/develop.yml
index 28509c3d..ab1adb7d 100644
--- a/.github/workflows/develop.yml
+++ b/.github/workflows/develop.yml
@@ -27,7 +27,7 @@ jobs:
       - name: Setup .NET
         uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: 8.0.x
+          dotnet-version: 9.0.x
       - name: Setup GitVersion
         uses: gittools/actions/gitversion/setup@v3.0.0
         with:
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index a6032768..527a96af 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -61,7 +61,7 @@ jobs:
       - name: Setup .NET
         uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: 8.0.x
+          dotnet-version: 9.0.x
       - name: Setup GitReleaseManager
         uses: gittools/actions/gitreleasemanager/setup@v3.0.0
         with:
diff --git a/Directory.Build.props b/Directory.Build.props
index 8b943f64..0740392c 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -1,6 +1,6 @@
 <Project>
     <PropertyGroup>
-        <TargetFramework>net8.0</TargetFramework>
+        <TargetFramework>net9.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
         <Nullable>enable</Nullable>
         <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
diff --git a/Readme.md b/Readme.md
index 1c2f3225..b13025ba 100644
--- a/Readme.md
+++ b/Readme.md
@@ -173,7 +173,7 @@ let s = v2d as string
 
 ### Требования
 
-- .NET 8 SDK
+- .NET 9 SDK
 
 ### Сборка
 После клонирования репозитория идём в папку проекта `HydraScript`.
diff --git a/src/Application/HydraScript.Application.StaticAnalysis/Impl/FunctionWithUndefinedReturnStorage.cs b/src/Application/HydraScript.Application.StaticAnalysis/Impl/FunctionWithUndefinedReturnStorage.cs
index 4de6ff44..b76cfac4 100644
--- a/src/Application/HydraScript.Application.StaticAnalysis/Impl/FunctionWithUndefinedReturnStorage.cs
+++ b/src/Application/HydraScript.Application.StaticAnalysis/Impl/FunctionWithUndefinedReturnStorage.cs
@@ -5,13 +5,11 @@ namespace HydraScript.Application.StaticAnalysis.Impl;
 
 internal class FunctionWithUndefinedReturnStorage : IFunctionWithUndefinedReturnStorage
 {
-    private readonly Dictionary<string, FunctionDeclaration> _declarations = [];
-    private readonly Dictionary<string, int> _keysWithOrder = [];
+    private readonly OrderedDictionary<string, FunctionDeclaration> _declarations = [];
 
     public void Save(FunctionSymbol symbol, FunctionDeclaration declaration)
     {
         _declarations[symbol.Id] = declaration;
-        _keysWithOrder[symbol.Id] = _declarations.Count;
     }
 
     public FunctionDeclaration Get(FunctionSymbol symbol)
@@ -19,22 +17,19 @@ public FunctionDeclaration Get(FunctionSymbol symbol)
         if (!_declarations.Remove(symbol.Id, out var declaration))
             throw new InvalidOperationException(message: "Cannot get function that has not been saved");
 
-        _keysWithOrder.Remove(symbol.Id);
         return declaration;
     }
 
     public void RemoveIfPresent(FunctionSymbol symbol)
     {
         _declarations.Remove(symbol.Id);
-        _keysWithOrder.Remove(symbol.Id);
     }
 
-    public IEnumerable<FunctionDeclaration> Flush() => _declarations
-        .OrderBy(kvp => _keysWithOrder[kvp.Key])
+    public IEnumerable<FunctionDeclaration> Flush() => _declarations.Keys.ToList()
         .Select(x =>
         {
-            _declarations.Remove(x.Key);
-            _keysWithOrder.Remove(x.Key);
-            return x.Value;
+            var decl = _declarations[x];
+            _declarations.Remove(x);
+            return decl;
         });
 }
\ No newline at end of file
diff --git a/tests/HydraScript.Tests/Unit/IR/FunctionWithUndefinedReturnStorageTests.cs b/tests/HydraScript.Tests/Unit/IR/FunctionWithUndefinedReturnStorageTests.cs
index d374898a..9c8f7a7a 100644
--- a/tests/HydraScript.Tests/Unit/IR/FunctionWithUndefinedReturnStorageTests.cs
+++ b/tests/HydraScript.Tests/Unit/IR/FunctionWithUndefinedReturnStorageTests.cs
@@ -11,10 +11,10 @@ namespace HydraScript.Tests.Unit.IR;
 
 public class FunctionWithUndefinedReturnStorageTests
 {
+    const string functionName = nameof(functionName);
     [Fact]
     public void StorageIsEmptyAfterFlushTest()
     {
-        const string functionName = nameof(functionName);
         IFunctionWithUndefinedReturnStorage storage = new FunctionWithUndefinedReturnStorage();
 
         var symbol = new FunctionSymbol(
@@ -36,4 +36,66 @@ public void StorageIsEmptyAfterFlushTest()
         
         Assert.Empty(storage.Flush());
     }
+
+    [Fact]
+    public void StorageIsCorrectOrderTest()
+    {
+        FunctionDeclaration[] declarations = [
+            new FunctionDeclaration(
+                name: new IdentifierReference(functionName),
+                returnTypeValue: Substitute.For<TypeValue>(),
+                arguments: [],
+                new BlockStatement([])),
+
+            new FunctionDeclaration(
+                name: new IdentifierReference(functionName),
+                returnTypeValue: Substitute.For<TypeValue>(),
+                arguments: [],
+                new BlockStatement([])),
+
+            new FunctionDeclaration(
+                name: new IdentifierReference(functionName),
+                returnTypeValue: Substitute.For<TypeValue>(),
+                arguments: [],
+                new BlockStatement([])),
+
+            new FunctionDeclaration(
+                name: new IdentifierReference(functionName),
+                returnTypeValue: Substitute.For<TypeValue>(),
+                arguments: [],
+                new BlockStatement([]))
+        ];
+        
+        IFunctionWithUndefinedReturnStorage storage = new FunctionWithUndefinedReturnStorage();
+
+        var removable = new FunctionSymbol(
+            id: "key2",
+            parameters: [],
+            "undefined",
+            isEmpty: false);
+
+        storage.Save(new FunctionSymbol(
+            id: "key1",
+            parameters: [],
+            "undefined",
+            isEmpty: false), declaration: declarations[0]);
+
+        storage.Save(removable, declaration: declarations[1]);
+
+        storage.Save(new FunctionSymbol(
+            id: "key3",
+            parameters: [],
+            "undefined",
+            isEmpty: false), declaration: declarations[2]);
+
+        storage.Save(new FunctionSymbol(
+            id: "key4",
+            parameters: [],
+            "undefined",
+            isEmpty: false), declaration: declarations[3]);
+
+        storage.RemoveIfPresent(removable);
+
+        Assert.Equal([declarations[0], declarations[2], declarations[3]], storage.Flush());
+    }
 }
\ No newline at end of file