diff --git a/generate/templates/Configuration.handlebars b/generate/templates/Configuration.handlebars
index 963a8f33..afd6ba27 100644
--- a/generate/templates/Configuration.handlebars
+++ b/generate/templates/Configuration.handlebars
@@ -351,7 +351,7 @@ namespace {{packageName}}.Client
         public string BuildUserAgent()
         {
             StringBuilder sb = new StringBuilder("vault-client-dotnet/");
-            string OSName = RuntimeInformation.OSDescription.Substring(0, RuntimeInformation.OSDescription.IndexOf(" "));
+            string OSName = RuntimeInformation.OSDescription.Contains(" ") ? RuntimeInformation.OSDescription.Substring(0, RuntimeInformation.OSDescription.IndexOf(" ")) : RuntimeInformation.OSDescription;
             sb.AppendFormat("{0} ({1} {2}; .Net {3})", Version, OSName, RuntimeInformation.ProcessArchitecture, System.Environment.Version);
             return sb.ToString();
         }
diff --git a/src/Vault/Client/Configuration.cs b/src/Vault/Client/Configuration.cs
index 9c79c5df..fb387b37 100644
--- a/src/Vault/Client/Configuration.cs
+++ b/src/Vault/Client/Configuration.cs
@@ -338,7 +338,7 @@ public string GetApiKeyWithPrefix(string apiKeyIdentifier)
         public string BuildUserAgent()
         {
             StringBuilder sb = new StringBuilder("vault-client-dotnet/");
-            string OSName = RuntimeInformation.OSDescription.Substring(0, RuntimeInformation.OSDescription.IndexOf(" "));
+            string OSName = RuntimeInformation.OSDescription.Contains(" ") ? RuntimeInformation.OSDescription.Substring(0, RuntimeInformation.OSDescription.IndexOf(" ")) : RuntimeInformation.OSDescription;
             sb.AppendFormat("{0} ({1} {2}; .Net {3})", Version, OSName, RuntimeInformation.ProcessArchitecture, System.Environment.Version);
             return sb.ToString();
         }