diff --git a/src/ComDiadocApi.cs b/src/ComDiadocApi.cs
index 82f474df..1feda8bf 100644
--- a/src/ComDiadocApi.cs
+++ b/src/ComDiadocApi.cs
@@ -4,6 +4,7 @@
 using System.Security;
 using Diadoc.Api.Com;
 using Diadoc.Api.Cryptography;
+using Diadoc.Api.Http;
 using Diadoc.Api.Proto;
 using Diadoc.Api.Proto.Certificates;
 using Diadoc.Api.Proto.Departments;
@@ -583,7 +584,9 @@ public class ComDiadocApi : SafeComObject, IComDiadocApi
 
 		public void Initialize(string apiClientId, string serverUrl)
 		{
-			diadoc = new DiadocApi(apiClientId, serverUrl, new WinApiCrypt());
+			var httpClient = new HttpClient(serverUrl);
+			httpClient.SetUserAgent(UserAgentBuilder.Build("COM"));
+			diadoc = new DiadocApi(new DiadocHttpApi(apiClientId, httpClient, new WinApiCrypt()));
 			DocflowApi = new ComDocflowApi(diadoc.Docflow);
 		}
 
diff --git a/src/Http/HttpClient.cs b/src/Http/HttpClient.cs
index 2b32f664..d189e250 100644
--- a/src/Http/HttpClient.cs
+++ b/src/Http/HttpClient.cs
@@ -38,6 +38,7 @@ public class HttpClient : IHttpClient
 		private readonly string baseUrl;
 		private NetworkCredential proxyCredential;
 		private Uri proxyUri;
+		private string userAgentString;
 
 		public HttpClient([NotNull] string baseUrl)
 		{
@@ -53,6 +54,7 @@ public HttpClient([NotNull] string baseUrl)
 
 			this.baseUrl = baseUrl.EndsWith("/") ? baseUrl.Substring(0, baseUrl.Length - 1) : baseUrl;
 			UseSystemProxy = true;
+			userAgentString = UserAgentBuilder.Build("C#");
 		}
 
 		/// <summary>
@@ -93,6 +95,11 @@ public void SetProxyCredentials([NotNull] string user, [NotNull] SecureString pa
 			proxyCredential = new NetworkCredential(userDomain.User, SecureStringToString(password), userDomain.Domain);
 		}
 
+		internal void SetUserAgent([NotNull] string userAgent)
+		{
+			userAgentString = userAgent ?? throw new ArgumentNullException(nameof(userAgent));
+		}
+
 		[NotNull]
 		private static string SecureStringToString([NotNull] SecureString secureString)
 		{
@@ -289,7 +296,7 @@ private WebRequest PrepareWebRequest([NotNull] HttpRequest request)
 				webRequest.ContentLength = 0;
 			}
 
-			webRequest.UserAgent = UserAgentString;
+			webRequest.UserAgent = userAgentString;
 			return webRequest;
 		}
 
@@ -304,33 +311,5 @@ private void ProxifyWebRequest([NotNull] WebRequest request)
 				request.Proxy.Credentials = proxyCredential;
 			}
 		}
-
-		private static string UserAgentString { get; set; }
-
-		static HttpClient()
-		{
-			string sdkVersion = typeof(HttpClient).Assembly.GetName().Version.ToString();
-			string netFxVersion = Environment.Version.ToString();
-			try
-			{
-				sdkVersion = FileVersionInfo.GetVersionInfo(typeof(HttpClient).Assembly.Location).FileVersion;
-			}
-			catch
-			{
-			}
-
-			try
-			{
-				netFxVersion = FileVersionInfo.GetVersionInfo(typeof(int).Assembly.Location).FileVersion;
-			}
-			catch
-			{
-			}
-
-			UserAgentString = string.Format("Diadoc C# SDK={0};OS={1};NETFX={2}",
-				sdkVersion,
-				Environment.OSVersion.VersionString,
-				netFxVersion);
-		}
 	}
 }
diff --git a/src/Http/UserAgentBuilder.cs b/src/Http/UserAgentBuilder.cs
new file mode 100644
index 00000000..8e5d329d
--- /dev/null
+++ b/src/Http/UserAgentBuilder.cs
@@ -0,0 +1,44 @@
+using System;
+using System.Diagnostics;
+using JetBrains.Annotations;
+
+namespace Diadoc.Api.Http
+{
+	internal static class UserAgentBuilder
+	{
+		private static readonly string SdkVersion;
+		private static readonly string NetFxVersion;
+
+		static UserAgentBuilder()
+		{
+			SdkVersion = typeof(HttpClient).Assembly.GetName().Version.ToString();
+			NetFxVersion = Environment.Version.ToString();
+			try
+			{
+				SdkVersion = FileVersionInfo.GetVersionInfo(typeof(HttpClient).Assembly.Location).FileVersion;
+			}
+			catch
+			{
+			}
+
+			try
+			{
+				NetFxVersion = FileVersionInfo.GetVersionInfo(typeof(int).Assembly.Location).FileVersion;
+			}
+			catch
+			{
+			}
+		}
+		
+		public static string Build([NotNull] string sdkName)
+		{
+			if (sdkName == null)
+				throw new ArgumentNullException(nameof(sdkName));
+			return string.Format("Diadoc {0} SDK={1};OS={2};NETFX={3}",
+				sdkName,
+				SdkVersion,
+				Environment.OSVersion.VersionString,
+				NetFxVersion);
+		}
+	}
+}
diff --git a/tests/DiadocApi-Tests.csproj b/tests/DiadocApi-Tests.csproj
index 6d27449c..966f632a 100644
--- a/tests/DiadocApi-Tests.csproj
+++ b/tests/DiadocApi-Tests.csproj
@@ -2,7 +2,7 @@
   <PropertyGroup>
     <RootNamespace>Diadoc.Api.Tests</RootNamespace>
     <AssemblyName>DiadocApi.Tests</AssemblyName>
-    <TargetFrameworks>net35;net40;net45;net461;net472;netcoreapp2.2</TargetFrameworks>
+    <TargetFrameworks>net35;net40;net45;net461;net472;net5.0</TargetFrameworks>
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
     <OutputPath>$(SolutionDir)\bin\$(Configuration)\$(AssemblyName)\</OutputPath>
   </PropertyGroup>