diff --git a/src/Examples/Brainfuck/Brainfuck.csproj b/src/Examples/Brainfuck/Brainfuck.csproj
index dfb51603..76a54bd3 100644
--- a/src/Examples/Brainfuck/Brainfuck.csproj
+++ b/src/Examples/Brainfuck/Brainfuck.csproj
@@ -17,6 +17,5 @@
     <PackageReference Include="Mono.Cecil" />
     <PackageReference Include="Pixie" />
     <PackageReference Include="Pixie.Loyc" />
-    <PackageReference Include="System.Collections.Immutable" />
   </ItemGroup>
 </Project>
diff --git a/src/Flame.Clr/Flame.Clr.csproj b/src/Flame.Clr/Flame.Clr.csproj
index 4f9bcae5..2dfe32f6 100644
--- a/src/Flame.Clr/Flame.Clr.csproj
+++ b/src/Flame.Clr/Flame.Clr.csproj
@@ -31,6 +31,5 @@
     <ProjectReference Include="..\Flame\Flame.csproj" />
     <ProjectReference Include="..\Flame.Compiler\Flame.Compiler.csproj" />
     <PackageReference Include="Mono.Cecil" />
-    <PackageReference Include="System.Collections.Immutable" />
   </ItemGroup>
 </Project>
diff --git a/src/Flame.Compiler/Flame.Compiler.csproj b/src/Flame.Compiler/Flame.Compiler.csproj
index fca547b5..eb0ba1bb 100644
--- a/src/Flame.Compiler/Flame.Compiler.csproj
+++ b/src/Flame.Compiler/Flame.Compiler.csproj
@@ -29,6 +29,6 @@
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="..\Flame\Flame.csproj" />
-    <PackageReference Include="System.Collections.Immutable" />
+    <PackageReference Include="System.Collections.Immutable" Condition="'$(TargetFramework)' == 'netstandard2.0' OR '$(TargetFramework)' == 'net472'" />
   </ItemGroup>
 </Project>
diff --git a/src/Flame.Ir/Flame.Ir.csproj b/src/Flame.Ir/Flame.Ir.csproj
index 4d7826d5..68ee05fe 100644
--- a/src/Flame.Ir/Flame.Ir.csproj
+++ b/src/Flame.Ir/Flame.Ir.csproj
@@ -35,6 +35,5 @@
     <PackageReference Include="Loyc.Syntax" />
     <PackageReference Include="Pixie" />
     <PackageReference Include="Pixie.Loyc" />
-    <PackageReference Include="System.Collections.Immutable" />
   </ItemGroup>
 </Project>
diff --git a/src/Flame.Llvm/Flame.Llvm.csproj b/src/Flame.Llvm/Flame.Llvm.csproj
index c7254e4e..ea33ca3a 100644
--- a/src/Flame.Llvm/Flame.Llvm.csproj
+++ b/src/Flame.Llvm/Flame.Llvm.csproj
@@ -8,8 +8,7 @@
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="LLVMSharp" />
-    <PackageReference Include="System.Collections.Immutable" />
+    <PackageReference Include="LLVMSharp" />
     <ProjectReference Include="..\Flame\Flame.csproj" />
     <ProjectReference Include="..\Flame.Compiler\Flame.Compiler.csproj" />
   </ItemGroup>
diff --git a/src/IL2LLVM/IL2LLVM.csproj b/src/IL2LLVM/IL2LLVM.csproj
index 25f3319d..705967bc 100644
--- a/src/IL2LLVM/IL2LLVM.csproj
+++ b/src/IL2LLVM/IL2LLVM.csproj
@@ -18,7 +18,6 @@
     <PackageReference Include="Mono.Cecil" />
     <PackageReference Include="Pixie" />
     <PackageReference Include="Pixie.Loyc" />
-    <PackageReference Include="System.Collections.Immutable" />
     <PackageReference Include="LLVMSharp" />
   </ItemGroup>
 </Project>
diff --git a/src/ILOpt/ILOpt.csproj b/src/ILOpt/ILOpt.csproj
index 4871d2f5..91b72c59 100644
--- a/src/ILOpt/ILOpt.csproj
+++ b/src/ILOpt/ILOpt.csproj
@@ -17,6 +17,5 @@
     <PackageReference Include="Mono.Cecil" />
     <PackageReference Include="Pixie" />
     <PackageReference Include="Pixie.Loyc" />
-    <PackageReference Include="System.Collections.Immutable" />
   </ItemGroup>
 </Project>
diff --git a/src/UnitTests/UnitTests.csproj b/src/UnitTests/UnitTests.csproj
index 23efab9b..5b5bde48 100644
--- a/src/UnitTests/UnitTests.csproj
+++ b/src/UnitTests/UnitTests.csproj
@@ -27,6 +27,5 @@
     <PackageReference Include="NUnit3TestAdapter" />
     <PackageReference Include="Pixie" />
     <PackageReference Include="Pixie.Loyc" />
-    <PackageReference Include="System.Collections.Immutable" />
   </ItemGroup>
 </Project>