diff --git a/src/Confluent.SchemaRegistry.Serdes.Protobuf/Confluent.SchemaRegistry.Serdes.Protobuf.csproj b/src/Confluent.SchemaRegistry.Serdes.Protobuf/Confluent.SchemaRegistry.Serdes.Protobuf.csproj
index 052c02d56..6fff0d7f1 100644
--- a/src/Confluent.SchemaRegistry.Serdes.Protobuf/Confluent.SchemaRegistry.Serdes.Protobuf.csproj
+++ b/src/Confluent.SchemaRegistry.Serdes.Protobuf/Confluent.SchemaRegistry.Serdes.Protobuf.csproj
@@ -22,7 +22,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Google.Protobuf" Version="3.11.2" />
+    <PackageReference Include="Google.Protobuf" Version="3.15.6" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/test/Confluent.SchemaRegistry.IntegrationTests/Confluent.SchemaRegistry.IntegrationTests.csproj b/test/Confluent.SchemaRegistry.IntegrationTests/Confluent.SchemaRegistry.IntegrationTests.csproj
old mode 100755
new mode 100644
index 4c43e251b..2e83b3f8a
--- a/test/Confluent.SchemaRegistry.IntegrationTests/Confluent.SchemaRegistry.IntegrationTests.csproj
+++ b/test/Confluent.SchemaRegistry.IntegrationTests/Confluent.SchemaRegistry.IntegrationTests.csproj
@@ -25,7 +25,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.0.0" />
     <PackageReference Include="xunit" Version="2.2.0" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.2.0" />
-    <PackageReference Include="Google.Protobuf" Version="3.11.2" />
+    <PackageReference Include="Google.Protobuf" Version="3.15.6" />
     <PackageReference Include="NJsonSchema" Version="10.1.5" />
   </ItemGroup>
 
diff --git a/test/Confluent.SchemaRegistry.Serdes.UnitTests/Confluent.SchemaRegistry.Serdes.UnitTests.csproj b/test/Confluent.SchemaRegistry.Serdes.UnitTests/Confluent.SchemaRegistry.Serdes.UnitTests.csproj
index dd7189c5b..fdd873e2e 100644
--- a/test/Confluent.SchemaRegistry.Serdes.UnitTests/Confluent.SchemaRegistry.Serdes.UnitTests.csproj
+++ b/test/Confluent.SchemaRegistry.Serdes.UnitTests/Confluent.SchemaRegistry.Serdes.UnitTests.csproj
@@ -12,7 +12,7 @@
     <PackageReference Include="Moq" Version="4.7.99" />
     <PackageReference Include="xunit" Version="2.2.0" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.2.0" />
-    <PackageReference Include="Google.Protobuf" Version="3.11.3" />
+    <PackageReference Include="Google.Protobuf" Version="3.15.6" />
     <PackageReference Include="Apache.Avro" Version="1.10.1" />
     <PackageReference Include="System.Runtime" Version="4.3" />
   </ItemGroup>