diff --git a/src/EnumUtilities/EnumUtilities.csproj b/src/EnumUtilities/EnumUtilities.csproj
index af59a98..c17d2eb 100644
--- a/src/EnumUtilities/EnumUtilities.csproj
+++ b/src/EnumUtilities/EnumUtilities.csproj
@@ -17,7 +17,7 @@
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     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.3.1" PrivateAssets="all" />
-    <PackageReference Include="Polyfill" Version="4.9.0">
+    <PackageReference Include="Polyfill" Version="5.1.0">
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       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
diff --git a/src/EnumUtilities/packages.lock.json b/src/EnumUtilities/packages.lock.json
index acd1092..9c986cf 100644
--- a/src/EnumUtilities/packages.lock.json
+++ b/src/EnumUtilities/packages.lock.json
@@ -46,9 +46,9 @@
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+        "requested": "[5.1.0, )",
+        "resolved": "5.1.0",
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       },
       "Microsoft.Build.Tasks.Git": {
         "type": "Transitive",