diff --git a/flang/unittests/RuntimeGTest/CrashHandlerFixture.cpp b/flang/unittests/RuntimeGTest/CrashHandlerFixture.cpp
--- a/flang/unittests/RuntimeGTest/CrashHandlerFixture.cpp
+++ b/flang/unittests/RuntimeGTest/CrashHandlerFixture.cpp
@@ -28,7 +28,7 @@
 // Register the crash handler above when creating each unit test in this suite
 void CrashHandlerFixture::SetUp() {
   static bool isCrashHanlderRegistered{false};
-  if (not isCrashHanlderRegistered)
+  if (!isCrashHanlderRegistered)
     Fortran::runtime::Terminator::RegisterCrashHandler(CatchCrash);
   isCrashHanlderRegistered = true;
 }