diff --git a/src/Microsoft.Identity.Web/AppServicesAuth/AppServicesAuthenticationInformation.cs b/src/Microsoft.Identity.Web/AppServicesAuth/AppServicesAuthenticationInformation.cs
index 9e1868905..a14e2113e 100644
--- a/src/Microsoft.Identity.Web/AppServicesAuth/AppServicesAuthenticationInformation.cs
+++ b/src/Microsoft.Identity.Web/AppServicesAuth/AppServicesAuthenticationInformation.cs
@@ -16,18 +16,18 @@ namespace Microsoft.Identity.Web
     public static class AppServicesAuthenticationInformation
     {
         // Environment variables.
-        private const string AppServicesAuthEnabledEnvironmentVariable = "WEBSITE_AUTH_ENABLED";            // True
-        private const string AppServicesAuthOpenIdIssuerEnvironmentVariable = "WEBSITE_AUTH_OPENID_ISSUER"; // for instance https://sts.windows.net/<tenantId>/
-        private const string AppServicesAuthClientIdEnvironmentVariable = "WEBSITE_AUTH_CLIENT_ID";         // A GUID
-        private const string AppServicesAuthClientSecretEnvironmentVariable = "WEBSITE_AUTH_CLIENT_SECRET"; // A string
-        private const string AppServicesAuthLogoutPathEnvironmentVariable = "WEBSITE_AUTH_LOGOUT_PATH";    // /.auth/logout
-        private const string AppServicesAuthIdentityProviderEnvironmentVariable = "WEBSITE_AUTH_DEFAULT_PROVIDER"; // AzureActiveDirectory
-        private const string AppServicesAuthAzureActiveDirectory = "AzureActiveDirectory";
-        private const string AppServicesAuthIdTokenHeader = "X-MS-TOKEN-AAD-ID-TOKEN";
+        internal const string AppServicesAuthEnabledEnvironmentVariable = "WEBSITE_AUTH_ENABLED";            // True
+        internal const string AppServicesAuthOpenIdIssuerEnvironmentVariable = "WEBSITE_AUTH_OPENID_ISSUER"; // for instance https://sts.windows.net/<tenantId>/
+        internal const string AppServicesAuthClientIdEnvironmentVariable = "WEBSITE_AUTH_CLIENT_ID";         // A GUID
+        internal const string AppServicesAuthClientSecretEnvironmentVariable = "WEBSITE_AUTH_CLIENT_SECRET"; // A string
+        internal const string AppServicesAuthLogoutPathEnvironmentVariable = "WEBSITE_AUTH_LOGOUT_PATH";    // /.auth/logout
+        internal const string AppServicesAuthIdentityProviderEnvironmentVariable = "WEBSITE_AUTH_DEFAULT_PROVIDER"; // AzureActiveDirectory
+        internal const string AppServicesAuthAzureActiveDirectory = "AzureActiveDirectory";
+        internal const string AppServicesAuthIdTokenHeader = "X-MS-TOKEN-AAD-ID-TOKEN";
         private const string AppServicesAuthIdpTokenHeader = "X-MS-CLIENT-PRINCIPAL-IDP";
 
         // Artificially added by Microsoft.Identity.Web to help debugging App Services. See the Debug controller of the test app
-        private const string AppServicesAuthDebugHeadersEnvironmentVariable = "APP_SERVICES_AUTH_LOCAL_DEBUG";
+        internal const string AppServicesAuthDebugHeadersEnvironmentVariable = "APP_SERVICES_AUTH_LOCAL_DEBUG";
 
         /// <summary>
         /// Is App Services authentication enabled?.
@@ -36,8 +36,17 @@ public static bool IsAppServicesAadAuthenticationEnabled
         {
             get
             {
-                return (Environment.GetEnvironmentVariable(AppServicesAuthEnabledEnvironmentVariable) == Constants.True)
-                    && Environment.GetEnvironmentVariable(AppServicesAuthIdentityProviderEnvironmentVariable) == AppServicesAuthAzureActiveDirectory;
+                return
+
+                    string.Equals(
+                        Environment.GetEnvironmentVariable(AppServicesAuthEnabledEnvironmentVariable),
+                        Constants.True,
+                        StringComparison.OrdinalIgnoreCase) &&
+
+                     string.Equals(
+                         Environment.GetEnvironmentVariable(AppServicesAuthIdentityProviderEnvironmentVariable),
+                         AppServicesAuthAzureActiveDirectory,
+                         StringComparison.OrdinalIgnoreCase);
             }
         }
 
@@ -93,7 +102,7 @@ internal static string? Issuer
         {
             string? headerPlusValue = Environment.GetEnvironmentVariable(AppServicesAuthDebugHeadersEnvironmentVariable)
                 ?.Split(';')
-                ?.FirstOrDefault(h => h.StartsWith(header));
+                ?.FirstOrDefault(h => h.StartsWith(header, StringComparison.OrdinalIgnoreCase));
             return headerPlusValue?.Substring(header.Length + 1);
         }
 #endif
diff --git a/tests/Microsoft.Identity.Web.Test/AppServicesAuthenticationInformationTests.cs b/tests/Microsoft.Identity.Web.Test/AppServicesAuthenticationInformationTests.cs
new file mode 100644
index 000000000..718e51ca9
--- /dev/null
+++ b/tests/Microsoft.Identity.Web.Test/AppServicesAuthenticationInformationTests.cs
@@ -0,0 +1,43 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Microsoft.Extensions.Primitives;
+using Xunit;
+
+namespace Microsoft.Identity.Web.Test
+{
+    public class AppServicesAuthenticationInformationTests
+    {
+        [Fact]
+        public void SimulateGetttingHeaderFromDebugEnvironmentVariable()
+        {
+            try
+            {
+                Environment.SetEnvironmentVariable(
+                  AppServicesAuthenticationInformation.AppServicesAuthDebugHeadersEnvironmentVariable,
+                  $"a;{AppServicesAuthenticationInformation.AppServicesAuthIdTokenHeader}:xyz");
+
+                var res = AppServicesAuthenticationInformation.GetIdToken(
+                    new Dictionary<string, StringValues>()
+                    {
+                        { AppServicesAuthenticationInformation.AppServicesAuthIdTokenHeader, new StringValues(string.Empty) },
+                    });
+
+#if DEBUG
+                Assert.Equal("xyz", res);
+#else
+                Assert.Equal(string.Empty, res);
+#endif
+            }
+            finally
+            {
+                Environment.SetEnvironmentVariable(
+                   AppServicesAuthenticationInformation.AppServicesAuthDebugHeadersEnvironmentVariable,
+                   string.Empty);
+            }
+        }
+    }
+}
diff --git a/tests/Microsoft.Identity.Web.Test/WebAppExtensionsTests.cs b/tests/Microsoft.Identity.Web.Test/WebAppExtensionsTests.cs
index 53025e861..a17e1a500 100644
--- a/tests/Microsoft.Identity.Web.Test/WebAppExtensionsTests.cs
+++ b/tests/Microsoft.Identity.Web.Test/WebAppExtensionsTests.cs
@@ -59,10 +59,21 @@ public class WebAppExtensionsTests
 
         public WebAppExtensionsTests()
         {
+            ResetAppServiceEnv();
             _configSection = GetConfigSection(ConfigSectionName);
             _env = new HostingEnvironment { EnvironmentName = Environments.Development };
         }
 
+        private void ResetAppServiceEnv()
+        {
+            Environment.SetEnvironmentVariable(AppServicesAuthenticationInformation.AppServicesAuthEnabledEnvironmentVariable, string.Empty);
+            Environment.SetEnvironmentVariable(AppServicesAuthenticationInformation.AppServicesAuthIdentityProviderEnvironmentVariable, string.Empty);
+            Environment.SetEnvironmentVariable(AppServicesAuthenticationInformation.AppServicesAuthClientIdEnvironmentVariable, string.Empty);
+            Environment.SetEnvironmentVariable(AppServicesAuthenticationInformation.AppServicesAuthClientSecretEnvironmentVariable, string.Empty);
+            Environment.SetEnvironmentVariable(AppServicesAuthenticationInformation.AppServicesAuthLogoutPathEnvironmentVariable, string.Empty);
+            Environment.SetEnvironmentVariable(AppServicesAuthenticationInformation.AppServicesAuthIdentityProviderEnvironmentVariable, string.Empty);
+        }
+
         [Theory]
         [InlineData(true)]
         [InlineData(false)]
@@ -411,6 +422,39 @@ public void AddMicrosoftIdentityWebApp_AddsInMemoryTokenCaches()
             Assert.Contains(services, s => s.ServiceType == typeof(IMsalTokenCacheProvider));
         }
 
+        [Theory]
+        [InlineData("tRue", "azureactivedirectory")]
+        [InlineData("true", "azureactivedirectory")]
+        [InlineData("tRue", AppServicesAuthenticationInformation.AppServicesAuthAzureActiveDirectory)]
+        [InlineData("true", AppServicesAuthenticationInformation.AppServicesAuthAzureActiveDirectory)]
+        // Regression for https://github.com/AzureAD/microsoft-identity-web/issues/1163
+        public void AppServices_EnvironmentTest(string appServicesEnvEnabledValue, string idpEnvValue)
+        {
+            try
+            {
+                // Arrange
+                Environment.SetEnvironmentVariable(
+                    AppServicesAuthenticationInformation.AppServicesAuthEnabledEnvironmentVariable, appServicesEnvEnabledValue);
+
+                Environment.SetEnvironmentVariable(
+                    AppServicesAuthenticationInformation.AppServicesAuthIdentityProviderEnvironmentVariable,
+                    idpEnvValue);
+
+                var services = new ServiceCollection();
+
+                // Act
+                services.AddAuthentication(OpenIdConnectDefaults.AuthenticationScheme)
+                    .AddMicrosoftIdentityWebApp(_configureMsOptions);
+
+                // Assert
+                Assert.Contains(services, s => s.ServiceType == typeof(AppServicesAuthenticationHandler));
+            }
+            finally
+            {
+                ResetAppServiceEnv();
+            }
+        }
+
         [Fact]
         public void AddMicrosoftGraphUsingFactoryFunction()
         {
@@ -552,6 +596,8 @@ private void AddMicrosoftIdentityWebApp_TestCommon(IServiceCollection services,
             Assert.Contains(services, s => s.ServiceType == typeof(IConfigureOptions<OpenIdConnectOptions>));
             Assert.Contains(services, s => s.ServiceType == typeof(IConfigureOptions<MicrosoftIdentityOptions>));
             Assert.Contains(services, s => s.ServiceType == typeof(IPostConfigureOptions<CookieAuthenticationOptions>));
+            Assert.DoesNotContain(services, s => s.ServiceType == typeof(AppServicesAuthenticationHandler));
+
             Assert.Equal(ServiceLifetime.Singleton, services.First(s => s.ServiceType == typeof(MicrosoftIdentityIssuerValidatorFactory)).Lifetime);
 
             // Assert properties set
@@ -634,7 +680,7 @@ private async Task AddMicrosoftIdentityWebApp_TestB2cSpecificSetup(IServiceColle
 
             await remoteFailureFuncMock.ReceivedWithAnyArgs().Invoke(Arg.Any<RemoteFailureContext>()).ConfigureAwait(false);
             // Assert issuer is updated to non-default user flow
-            Assert.Contains(TestConstants.B2CEditProfileUserFlow, redirectContext.ProtocolMessage.IssuerAddress);
+            Assert.Contains(TestConstants.B2CEditProfileUserFlow, redirectContext.ProtocolMessage.IssuerAddress, System.StringComparison.OrdinalIgnoreCase);
             Assert.NotNull(redirectContext.ProtocolMessage.Parameters[ClaimConstants.ClientInfo]);
             Assert.Equal(Constants.One, redirectContext.ProtocolMessage.Parameters[ClaimConstants.ClientInfo].ToString(CultureInfo.InvariantCulture));
         }