diff --git a/AsyncVoidAnalyzer.Test/packages.config b/AsyncVoidAnalyzer.Test/packages.config
index 32556cb..642f813 100644
--- a/AsyncVoidAnalyzer.Test/packages.config
+++ b/AsyncVoidAnalyzer.Test/packages.config
@@ -8,6 +8,6 @@
   <package id="Microsoft.CodeAnalysis.VisualBasic.Workspaces" version="1.0.0" targetFramework="net452" />
   <package id="Microsoft.CodeAnalysis.Workspaces.Common" version="1.0.0" targetFramework="net452" />
   <package id="Microsoft.Composition" version="1.0.27" targetFramework="net452" />
-  <package id="System.Collections.Immutable" version="1.1.36" targetFramework="net452" />
+  <package id="System.Collections.Immutable" version="1.5.0" targetFramework="net452" />
   <package id="System.Reflection.Metadata" version="1.0.21" targetFramework="net452" />
 </packages>
\ No newline at end of file
diff --git a/AsyncVoidAnalyzer/packages.config b/AsyncVoidAnalyzer/packages.config
index 40bf2c2..c50a1ef 100644
--- a/AsyncVoidAnalyzer/packages.config
+++ b/AsyncVoidAnalyzer/packages.config
@@ -7,6 +7,6 @@
   <package id="Microsoft.CodeAnalysis.Workspaces.Common" version="1.0.0" targetFramework="portable45-net45+win8" />
   <package id="Microsoft.Composition" version="1.0.27" targetFramework="portable45-net45+win8" />
   <package id="NuGet.CommandLine" version="2.8.5" targetFramework="portable45-net45+win8" />
-  <package id="System.Collections.Immutable" version="1.1.36" targetFramework="portable45-net45+win8" />
+  <package id="System.Collections.Immutable" version="1.5.0" targetFramework="portable45-net45+win8" />
   <package id="System.Reflection.Metadata" version="1.0.21" targetFramework="portable45-net45+win8" />
 </packages>
\ No newline at end of file