diff --git a/TeamCity.VSTest.TestLogger/FailedTestsReportWriter.cs b/TeamCity.VSTest.TestLogger/FailedTestsReportWriter.cs
index 3789b52..c69d938 100644
--- a/TeamCity.VSTest.TestLogger/FailedTestsReportWriter.cs
+++ b/TeamCity.VSTest.TestLogger/FailedTestsReportWriter.cs
@@ -45,7 +45,7 @@ public void ReportFailedTest(TestCase testCase)
         if (_reportWriter == null)
             return;
 
-        if (string.IsNullOrWhiteSpace(testCase.FullyQualifiedName))
+        if (Strings.IsNullOrWhiteSpace(testCase.FullyQualifiedName))
             return;
 
         var testName = GetTestNameForRetry(testCase.FullyQualifiedName);