diff --git a/src/Rsk.TokenExchange/Validators/DefaultTokenExchangeRequestValidator.cs b/src/Rsk.TokenExchange/Validators/DefaultTokenExchangeRequestValidator.cs
index 16c4d02..3a1a1e6 100644
--- a/src/Rsk.TokenExchange/Validators/DefaultTokenExchangeRequestValidator.cs
+++ b/src/Rsk.TokenExchange/Validators/DefaultTokenExchangeRequestValidator.cs
@@ -32,14 +32,14 @@ public async Task<ITokenExchangeValidationResult> Validate(ITokenExchangeRequest
             var result = await subjectTokenValidator.Validate(request.SubjectToken, request.SubjectTokenType);
 
             // validate that the requester is an intended audience of the subject token
-            var audiences = result.Claims.Where(x => x.Type == "aud").ToList();
-            var clientId = result.Claims.FirstOrDefault(x => x.Type == "client_id");
-            if (audiences.All(x => x.Value != request.ClientId) && clientId?.Value != request.ClientId)
+            var audiences = result.Claims?.Where(x => x.Type == "aud").ToList();
+            var clientId = result.Claims?.FirstOrDefault(x => x.Type == "client_id");
+            if (audiences != null && audiences.All(x => x.Value != request.ClientId) && clientId?.Value != request.ClientId)
             {
                 return TokenExchangeValidationResult.Failure("Requester must be a recipient of the subject token");
             }
 
-            return result.IsValid 
+            return result.IsValid
                 ? TokenExchangeValidationResult.Success(result.Claims)
                 : TokenExchangeValidationResult.Failure("Invalid subject token");
         }
diff --git a/test/Rsk.TokenExchange.Tests/Validators/DefaultTokenExchangeRequestValidatorTests.cs b/test/Rsk.TokenExchange.Tests/Validators/DefaultTokenExchangeRequestValidatorTests.cs
index 7ae6899..c99bcdc 100644
--- a/test/Rsk.TokenExchange.Tests/Validators/DefaultTokenExchangeRequestValidatorTests.cs
+++ b/test/Rsk.TokenExchange.Tests/Validators/DefaultTokenExchangeRequestValidatorTests.cs
@@ -97,6 +97,23 @@ public async Task Validate_WhenSubjectTokenIsValidWithInvalidAudience_ExpectFail
             result.ErrorDescription.Should().NotBeNullOrWhiteSpace();
         }
 
+        [Fact]
+        public async Task Validate_WhenValidateReturnsInvalidAndExpectedClaimsAreNull_ExpectIsValidToBeFalse()
+        {
+            const string validClientId = "app1";
+            
+            mockRequest.Setup(x => x.ClientId).Returns(validClientId);
+            
+            mockSubjectTokenResponse.Setup(x => x.IsValid).Returns(false);
+            mockSubjectTokenResponse.Setup(x => x.Claims).Returns((IEnumerable<Claim>)null);
+
+            var sut = CreateSut();
+            var result = await sut.Validate(mockRequest.Object);
+
+            result.IsValid.Should().BeFalse();
+            result.Claims.Should().BeNull();
+        }
+        
         [Fact]
         public async Task Validate_WhenSubjectTokenIsValidAndAuthorizedWithCorrectClientId_ExpectSuccessResult()
         {