diff --git a/tools/ArielToMantidXML/ArielToMantidXML/AssReader.h b/tools/ArielToMantidXML/ArielToMantidXML/AssReader.h
index dbf427d3255ed0f1af2a8d9903e1aa0a63fce370..64220a8d4af987e14f43af681878e13ca7ac5c31 100644
--- a/tools/ArielToMantidXML/ArielToMantidXML/AssReader.h
+++ b/tools/ArielToMantidXML/ArielToMantidXML/AssReader.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef ASSREADER_H_
-#define ASSREADER_H_
+#pragma once
 
 #include <fstream>
 #include <string>
@@ -24,5 +23,3 @@ public:
 private:
   std::ifstream m_assfile;
 };
-
-#endif
diff --git a/tools/ArielToMantidXML/ArielToMantidXML/Component.h b/tools/ArielToMantidXML/ArielToMantidXML/Component.h
index c80380cf2a1f03274e1be7f167c5d28c90bdcbef..12f9b3ec57c66a8ccdf732421c98fe33cd61e8df 100644
--- a/tools/ArielToMantidXML/ArielToMantidXML/Component.h
+++ b/tools/ArielToMantidXML/ArielToMantidXML/Component.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef COMPONENT_H_
-#define COMPONENT_H_
+#pragma once
 
 #include <string>
 #include <vector>
@@ -58,5 +57,3 @@ private:
   double m_r, m_theta, m_phi;
   //Mantid::Geometry::V3D m_pos;
 };
-
-#endif
diff --git a/tools/ArielToMantidXML/ArielToMantidXML/DatReader.h b/tools/ArielToMantidXML/ArielToMantidXML/DatReader.h
index c5a8552eba278bb77c69795496cb2b0738dbcc7b..8b171add6342e28104d1a1afe1f7776eea486b9a 100644
--- a/tools/ArielToMantidXML/ArielToMantidXML/DatReader.h
+++ b/tools/ArielToMantidXML/ArielToMantidXML/DatReader.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef DATREADER_H_
-#define DATREADER_H_
+#pragma once
 
 #include <fstream>
 #include <string>
@@ -24,5 +23,3 @@ public:
 private:
   std::ifstream m_datfile;
 };
-
-#endif
diff --git a/tools/ArielToMantidXML/ArielToMantidXML/XMLWriter.h b/tools/ArielToMantidXML/ArielToMantidXML/XMLWriter.h
index 4744a1f8681bf1d4e6e1d5115600d29a573f4ccc..2a2c8e773c949078b3504623e7db9cf0bf36d940 100644
--- a/tools/ArielToMantidXML/ArielToMantidXML/XMLWriter.h
+++ b/tools/ArielToMantidXML/ArielToMantidXML/XMLWriter.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef XMLWRITER_H_
-#define XMLWRITER_H_
+#pragma once
 
 #include <string>
 #include <fstream>
@@ -27,5 +26,3 @@ private:
   std::ofstream m_outputFile;
   Component* const m_startPoint;
 };
-
-#endif