diff --git a/src/Microsoft.IdentityModel.Validators/AadIssuerValidator/AadIssuerValidator.cs b/src/Microsoft.IdentityModel.Validators/AadIssuerValidator/AadIssuerValidator.cs
index b6cb627328..484e00f357 100644
--- a/src/Microsoft.IdentityModel.Validators/AadIssuerValidator/AadIssuerValidator.cs
+++ b/src/Microsoft.IdentityModel.Validators/AadIssuerValidator/AadIssuerValidator.cs
@@ -382,54 +382,34 @@ private ConfigurationManager<OpenIdConnectConfiguration> CreateConfigManager(
             }
         }
 
-        private static bool IsValidIssuer(string validIssuerTemplate, string tenantId, string actualIssuer)
+        internal static bool IsValidIssuer(string validIssuerTemplate, string tenantId, string actualIssuer)
         {
             if (string.IsNullOrEmpty(validIssuerTemplate))
                 return false;
 
+            ReadOnlySpan<char> validIssuerTemplateSpan = validIssuerTemplate.AsSpan();
+            ReadOnlySpan<char> actualIssuerSpan = actualIssuer.AsSpan();
             int indexOfTenantIdTemplate = validIssuerTemplate.IndexOf(TenantIdTemplate, StringComparison.Ordinal);
-            if (indexOfTenantIdTemplate >= 0)
+
+            if (indexOfTenantIdTemplate >= 0 && actualIssuer.Length > indexOfTenantIdTemplate)
             {
-                return IssuersWithTemplatesAreEqual(validIssuerTemplate.AsSpan(), TenantIdTemplate.AsSpan(), indexOfTenantIdTemplate, actualIssuer.AsSpan(), tenantId.AsSpan());
+                // ensure the first part of the validIssuerTemplate matches the first part of actualIssuer
+                if (!validIssuerTemplateSpan.Slice(0, indexOfTenantIdTemplate).SequenceEqual(actualIssuerSpan.Slice(0, indexOfTenantIdTemplate)))
+                    return false;
+
+                // ensure that actualIssuer contains the tenantId from indexOfTenantIdTemplate for the length of tenantId.Length
+                if (!actualIssuerSpan.Slice(indexOfTenantIdTemplate, tenantId.Length).SequenceEqual(tenantId.AsSpan()))
+                    return false;
+
+                // ensure the second halves are equal
+                return validIssuerTemplateSpan.Slice(indexOfTenantIdTemplate + TenantIdTemplate.Length).SequenceEqual(actualIssuerSpan.Slice(indexOfTenantIdTemplate + tenantId.Length));
             }
             else
             {
-                return validIssuerTemplate == actualIssuer;
+                return validIssuerTemplateSpan.SequenceEqual(actualIssuerSpan);
             }
         }
 
-        /// <summary>
-        /// Compare two Issuers with templates without string allocations.
-        /// This function replaces: issuer1.Replace(issuer1Template, tenantId) == issuer2
-        /// Example:
-        ///     issuer1 = "https://login.microsoftonline.com/{tenantid}/v2.0"
-        ///     issuer1Template = "{tenantid}"
-        ///     issuer2 = "https://login.microsoftonline.com/12345678/v2.0"
-        ///     tenantId = "12345678"
-        /// </summary>
-        internal static bool IssuersWithTemplatesAreEqual(ReadOnlySpan<char> issuer1, ReadOnlySpan<char> issuer1Template, int templateStartIndex, ReadOnlySpan<char> issuer2, ReadOnlySpan<char> tenantId)
-        {
-            if (templateStartIndex == -1)
-                return false;
-
-            // ensure the first part of the issuer1 matches the first part of issuer2
-            if (!issuer1.Slice(0, templateStartIndex).SequenceEqual(issuer2.Slice(0, templateStartIndex)))
-                return false;
-
-            // ensure that issuer2 contains the tenantId from templateStartIndex for the length of tenantId.Length
-            if (!issuer2.Slice(templateStartIndex, tenantId.Length).SequenceEqual(tenantId))
-                return false;
-
-            int secondHalfIssuer1StartIndex = templateStartIndex + issuer1Template.Length;
-            int secondHalfIssuer2StartIndex = templateStartIndex + tenantId.Length;
-
-            // ensure the second halves are equal
-            if (!issuer1.Slice(secondHalfIssuer1StartIndex).SequenceEqual(issuer2.Slice(secondHalfIssuer2StartIndex)))
-                return false;
-
-            return true;
-        }
-
         private void SetEffectiveLKGIssuer(string aadIssuer, ProtocolVersion protocolVersion, TimeSpan lastKnownGoodLifetime)
         {
             var issuerLKG = new IssuerLastKnownGood
diff --git a/src/Microsoft.IdentityModel.Validators/AadTokenValidationParametersExtension.cs b/src/Microsoft.IdentityModel.Validators/AadTokenValidationParametersExtension.cs
index 04e055fcec..c890232ed8 100644
--- a/src/Microsoft.IdentityModel.Validators/AadTokenValidationParametersExtension.cs
+++ b/src/Microsoft.IdentityModel.Validators/AadTokenValidationParametersExtension.cs
@@ -86,8 +86,8 @@ internal static bool ValidateIssuerSigningKey(SecurityKey securityKey, SecurityT
                 // 3. signing key issuers will never match sts.windows.net as v1 endpoint doesn't have issuers attached to keys
                 // v2TokenIssuer is the representation of Token.Issuer (if it was a v2 issuer)
                 int templateStartIndex = signingKeyIssuer.IndexOf(AadIssuerValidator.TenantIdTemplate, StringComparison.Ordinal);
-                if (!AadIssuerValidator.IssuersWithTemplatesAreEqual(signingKeyIssuer.AsSpan(), AadIssuerValidator.TenantIdTemplate.AsSpan(), templateStartIndex, tokenIssuer.AsSpan(), tenantIdFromToken.AsSpan())
-                        && !AadIssuerValidator.IssuersWithTemplatesAreEqual(signingKeyIssuer.AsSpan(), AadIssuerValidator.TenantIdTemplate.AsSpan(), templateStartIndex, openIdConnectConfiguration.Issuer == null ? [] : openIdConnectConfiguration.Issuer.AsSpan(), tenantIdFromToken.AsSpan()))
+                if (!AadIssuerValidator.IsValidIssuer(signingKeyIssuer, tenantIdFromToken, tokenIssuer)
+                    && !AadIssuerValidator.IsValidIssuer(signingKeyIssuer, tenantIdFromToken, openIdConnectConfiguration.Issuer == null ? string.Empty : openIdConnectConfiguration.Issuer))
                 {
                     string effectiveSigningKeyIssuer = templateStartIndex > -1 ? CreateIssuer(signingKeyIssuer, AadIssuerValidator.TenantIdTemplate, tenantIdFromToken, templateStartIndex) : signingKeyIssuer;
                     throw LogHelper.LogExceptionMessage(new SecurityTokenInvalidIssuerException(LogHelper.FormatInvariant(LogMessages.IDX40005, LogHelper.MarkAsNonPII(tokenIssuer), LogHelper.MarkAsNonPII(effectiveSigningKeyIssuer))));
diff --git a/test/Microsoft.IdentityModel.Validators.Tests/AadIssuerValidatorTests.cs b/test/Microsoft.IdentityModel.Validators.Tests/AadIssuerValidatorTests.cs
index 4acf55a0fa..9e9be589c8 100644
--- a/test/Microsoft.IdentityModel.Validators.Tests/AadIssuerValidatorTests.cs
+++ b/test/Microsoft.IdentityModel.Validators.Tests/AadIssuerValidatorTests.cs
@@ -1,46 +1,23 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
-using System;
 using Xunit;
 
 namespace Microsoft.IdentityModel.Validators.Tests
 {
     public class AadIssuerValidatorTests
     {
-        [Fact]
-        public static void IssuersWithTemplatesAreEqualTests_EqualIssuers()
-        { 
-            // arrange
-            var issuer1Template = "{tenantId}";
-            var issuer1 = ValidatorConstants.AadInstance + issuer1Template;
-            var issuer2Template = ValidatorConstants.TenantIdAsGuid;
-            var issuer2 = ValidatorConstants.AadInstance + issuer2Template;
-            int templateStartIndex = issuer1.IndexOf(issuer1Template);
-
-            // act
-            var result = AadIssuerValidator.IssuersWithTemplatesAreEqual(
-                issuer1.AsSpan(), issuer1Template.AsSpan(), templateStartIndex, issuer2.AsSpan(), issuer2Template.AsSpan());
-
-            // assert
-            Assert.True(result);
-        }
-
-        [Fact]
-        public static void IssuersWithTemplatesAreEqualTests_UnequalIssuers()
+        [Theory]
+        [InlineData(ValidatorConstants.AadInstance + AadIssuerValidator.TenantIdTemplate, ValidatorConstants.AadInstance + ValidatorConstants.TenantIdAsGuid, true)]
+        [InlineData(ValidatorConstants.AadInstancePPE + AadIssuerValidator.TenantIdTemplate, ValidatorConstants.AadInstance + ValidatorConstants.TenantIdAsGuid, false)]
+        [InlineData("", ValidatorConstants.AadInstance + ValidatorConstants.TenantIdAsGuid, false)]
+        [InlineData(ValidatorConstants.AadInstance + AadIssuerValidator.TenantIdTemplate, "", false)]
+        public static void IsValidIssuer_CanValidateTemplatedIssuers(string templatedIssuer, string issuer, bool expectedResult)
         {
-            // arrange
-            var issuer1Template = "{tenantId}";
-            var issuer1 = ValidatorConstants.AadInstancePPE + issuer1Template;
-            var issuer2Template = ValidatorConstants.TenantIdAsGuid;
-            var issuer2 = ValidatorConstants.AadInstance + issuer2Template;
-            int templateStartIndex = issuer1.IndexOf(issuer1Template);
-
             // act
-            var result = AadIssuerValidator.IssuersWithTemplatesAreEqual(
-                issuer1.AsSpan(), issuer1Template.AsSpan(), templateStartIndex, issuer2.AsSpan(), issuer2Template.AsSpan());
+            var result = AadIssuerValidator.IsValidIssuer(templatedIssuer, ValidatorConstants.TenantIdAsGuid, issuer);
 
             // assert
-            Assert.False(result);
+            Assert.Equal(expectedResult, result);
         }
     }
 }