diff --git a/Framework/Nexus/inc/MantidNexus/MuonNexusReader.h b/Framework/Nexus/inc/MantidNexus/MuonNexusReader.h
index ab2043c58ae358fc45cbcbec9053b3e05098a06e..ab72939b6a26f63663f7091c9e0500253a512752 100644
--- a/Framework/Nexus/inc/MantidNexus/MuonNexusReader.h
+++ b/Framework/Nexus/inc/MantidNexus/MuonNexusReader.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MUONNEXUSREADER_H
-#define MUONNEXUSREADER_H
+#pragma once
 
 #include "MantidAPI/Algorithm.h"
 #include "MantidDataObjects/Workspace2D.h"
@@ -99,5 +98,3 @@ public:
   int numDetectors;                      ///< detector count
   std::string getInstrumentName() const; ///< return instrument name
 };
-
-#endif /* MUONNEXUSREADER_H */
diff --git a/Framework/Nexus/inc/MantidNexus/NexusClasses.h b/Framework/Nexus/inc/MantidNexus/NexusClasses.h
index adc2f3640719c0c4b5f969aaa5132a59f975c4f3..d2803d98b5051810fd1e496a463a2e5d824c0a17 100644
--- a/Framework/Nexus/inc/MantidNexus/NexusClasses.h
+++ b/Framework/Nexus/inc/MantidNexus/NexusClasses.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_NEXUS_NEXUSCLASSES_H_
-#define MANTID_NEXUS_NEXUSCLASSES_H_
+#pragma once
 
 //----------------------------------------------------------------------
 // Includes
@@ -983,5 +982,3 @@ private:
 
 } // namespace NeXus
 } // namespace Mantid
-
-#endif /*MANTID_NEXUS_NEXUSCLASSES_H_*/
diff --git a/Framework/Nexus/inc/MantidNexus/NexusFileIO.h b/Framework/Nexus/inc/MantidNexus/NexusFileIO.h
index ad2160d59098f04c7e1e03b5aeab2fbf9e8f2aec..bc9d3476adf96b3b69774bc0aecb39ffec26ea04 100644
--- a/Framework/Nexus/inc/MantidNexus/NexusFileIO.h
+++ b/Framework/Nexus/inc/MantidNexus/NexusFileIO.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef NEXUSFILEIO_H
-#define NEXUSFILEIO_H
+#pragma once
 #include "MantidAPI/ITableWorkspace_fwd.h"
 #include "MantidAPI/MatrixWorkspace_fwd.h"
 #include "MantidAPI/Progress.h"
@@ -417,5 +416,3 @@ using NexusFileIO_sptr = boost::shared_ptr<NexusFileIO>;
 
 } // namespace NeXus
 } // namespace Mantid
-
-#endif /* NEXUSFILEIO_H */
diff --git a/Framework/Nexus/inc/MantidNexus/NexusIOHelper.h b/Framework/Nexus/inc/MantidNexus/NexusIOHelper.h
index c677272356c5913acad756632d548117fa50d875..f779a25b88dcb325d13fe9690bb90892efc18d20 100644
--- a/Framework/Nexus/inc/MantidNexus/NexusIOHelper.h
+++ b/Framework/Nexus/inc/MantidNexus/NexusIOHelper.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef NEXUSIOHELPER_H
-#define NEXUSIOHELPER_H
+#pragma once
 
 #include "MantidIndexing/DllConfig.h"
 #include <algorithm>
@@ -192,5 +191,3 @@ T readNexusValue(::NeXus::File &file, std::string entry = "") {
 } // namespace NeXusIOHelper
 } // namespace NeXus
 } // namespace Mantid
-
-#endif /* NEXUSIOHELPER_H */
diff --git a/Framework/Nexus/inc/MantidNexus/PrecompiledHeader.h b/Framework/Nexus/inc/MantidNexus/PrecompiledHeader.h
index 92e2614ddc564e979400275e26fe14b83408e9e1..cb11a20d7719e59e62a7d9a141aef7bb2dc8dd82 100644
--- a/Framework/Nexus/inc/MantidNexus/PrecompiledHeader.h
+++ b/Framework/Nexus/inc/MantidNexus/PrecompiledHeader.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_NEXUS_PRECOMPILEDHEADER_H_
-#define MANTID_NEXUS_PRECOMPILEDHEADER_H_
+#pragma once
 
 // NeXus
 #include "MantidNexusCPP/NeXusFile.hpp"
@@ -15,5 +14,3 @@
 #include <map>
 #include <string>
 #include <vector>
-
-#endif // MANTID_NEXUS_PRECOMPILEDHEADER_H_
\ No newline at end of file
diff --git a/Framework/Nexus/test/NexusIOHelperTest.h b/Framework/Nexus/test/NexusIOHelperTest.h
index 20bab472a208c2a39837e1bfae4ecbfe1821a92e..21c8e16e2782ea458265e518ef002850d0e3264d 100644
--- a/Framework/Nexus/test/NexusIOHelperTest.h
+++ b/Framework/Nexus/test/NexusIOHelperTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef NEXUSIOHELPERTEST_H_
-#define NEXUSIOHELPERTEST_H_
+#pragma once
 
 #include "MantidAPI/FileFinder.h"
 #include "MantidNexus/NexusIOHelper.h"
@@ -173,5 +172,3 @@ public:
     file.close();
   }
 };
-
-#endif /*NEXUSIOHELPERTEST_H_*/
diff --git a/Framework/NexusGeometry/inc/MantidNexusGeometry/AbstractLogger.h b/Framework/NexusGeometry/inc/MantidNexusGeometry/AbstractLogger.h
index f06543d9f0bd99bf959189689ab302c589ef393c..5eda71338ccbce434ffa08194ec17e3200cf267c 100644
--- a/Framework/NexusGeometry/inc/MantidNexusGeometry/AbstractLogger.h
+++ b/Framework/NexusGeometry/inc/MantidNexusGeometry/AbstractLogger.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_NEXUSGEOMETRY_ABSTRACTLOGGER_H_
-#define MANTID_NEXUSGEOMETRY_ABSTRACTLOGGER_H_
+#pragma once
 
 #include "MantidNexusGeometry/DllConfig.h"
 #include <memory>
@@ -63,5 +62,3 @@ template <typename T> std::unique_ptr<AbstractLogger> makeLogger(T *adaptee) {
 
 } // namespace NexusGeometry
 } // namespace Mantid
-
-#endif /* MANTID_NEXUSGEOMETRY_ABSTRACTLOGGER_H_ */
diff --git a/Framework/NexusGeometry/inc/MantidNexusGeometry/H5ForwardCompatibility.h b/Framework/NexusGeometry/inc/MantidNexusGeometry/H5ForwardCompatibility.h
index b4f8e0e0511e160293645907d57adf0aa20eb558..b75aaa976bcd33cb7e0f5c8563b0a14a10dadba7 100644
--- a/Framework/NexusGeometry/inc/MantidNexusGeometry/H5ForwardCompatibility.h
+++ b/Framework/NexusGeometry/inc/MantidNexusGeometry/H5ForwardCompatibility.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTIDNEXUSGEOMETRY_H5FORWARDCOMPATIBILITY
-#define MANTIDNEXUSGEOMETRY_H5FORWARDCOMPATIBILITY
+#pragma once
 
 #include "MantidNexusGeometry/DllConfig.h"
 #include <H5Cpp.h>
@@ -31,5 +30,3 @@ std::string getObjName(const H5::H5File &obj);
 } // namespace H5ForwardCompatibility
 } // namespace NexusGeometry
 } // namespace Mantid
-
-#endif // MANTIDNEXUSGEOMETRY_H5FORWARDCOMPATIBILITY
diff --git a/Framework/NexusGeometry/inc/MantidNexusGeometry/Hdf5Version.h b/Framework/NexusGeometry/inc/MantidNexusGeometry/Hdf5Version.h
index ef6a540214e42bc1b9376aefec09321afdfd0cea..eac70d50e16213794a3533df0fb8c6e1ff2375e0 100644
--- a/Framework/NexusGeometry/inc/MantidNexusGeometry/Hdf5Version.h
+++ b/Framework/NexusGeometry/inc/MantidNexusGeometry/Hdf5Version.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTIDHDF5_VERSION_H_
-#define MANTIDHDF5_VERSION_H_
+#pragma once
 
 #include "MantidNexusGeometry/DllConfig.h"
 
@@ -24,5 +23,3 @@ MANTID_NEXUSGEOMETRY_DLL bool checkVariableLengthStringSupport();
 } // namespace Hdf5Version
 } // namespace NexusGeometry
 } // namespace Mantid
-
-#endif // MANTIDHDF5_VERSION_H_
diff --git a/Framework/NexusGeometry/inc/MantidNexusGeometry/InstrumentBuilder.h b/Framework/NexusGeometry/inc/MantidNexusGeometry/InstrumentBuilder.h
index a0d114c2e4047de02e43ce946823f22487220081..945c94a296e6818b0fbaa0194ddd3ce5d8d97718 100644
--- a/Framework/NexusGeometry/inc/MantidNexusGeometry/InstrumentBuilder.h
+++ b/Framework/NexusGeometry/inc/MantidNexusGeometry/InstrumentBuilder.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTIDNEXUSGEOMETRY_INSTRUMENTBUILDER_H
-#define MANTIDNEXUSGEOMETRY_INSTRUMENTBUILDER_H
+#pragma once
 
 #include "MantidGeometry/IDTypes.h"
 #include "MantidGeometry/Objects/IObject.h"
@@ -80,5 +79,4 @@ private:
   Geometry::ICompAssembly *m_lastBank = nullptr;
 };
 } // namespace NexusGeometry
-} // namespace Mantid
-#endif // MANTIDNEXUSGEOMETRY_INSTRUMENTBUILDER_H
+} // namespace Mantid
\ No newline at end of file
diff --git a/Framework/NexusGeometry/inc/MantidNexusGeometry/JSONGeometryParser.h b/Framework/NexusGeometry/inc/MantidNexusGeometry/JSONGeometryParser.h
index 0a86afa45e4149d979f1717997cc52e93608db47..808ebcbec68a84943b66d61204b8fdbe4ee23808 100644
--- a/Framework/NexusGeometry/inc/MantidNexusGeometry/JSONGeometryParser.h
+++ b/Framework/NexusGeometry/inc/MantidNexusGeometry/JSONGeometryParser.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_NEXUSGEOMETRY_JSONGEOMETRYPARSER_H_
-#define MANTID_NEXUSGEOMETRY_JSONGEOMETRYPARSER_H_
+#pragma once
 
 #include "MantidGeometry/IDTypes.h"
 #include "MantidNexusGeometry/DllConfig.h"
@@ -188,5 +187,3 @@ private:
 
 } // namespace NexusGeometry
 } // namespace Mantid
-
-#endif /* MANTID_NEXUSGEOMETRY_JSONGEOMETRYPARSER_H_ */
diff --git a/Framework/NexusGeometry/inc/MantidNexusGeometry/JSONInstrumentBuilder.h b/Framework/NexusGeometry/inc/MantidNexusGeometry/JSONInstrumentBuilder.h
index 43b3adbc08fe006eaeeaff3c2e59ffd512c461bb..8a51283a03e88bcfc0f6036ca4b41094676bdf66 100644
--- a/Framework/NexusGeometry/inc/MantidNexusGeometry/JSONInstrumentBuilder.h
+++ b/Framework/NexusGeometry/inc/MantidNexusGeometry/JSONInstrumentBuilder.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_NEXUSGEOMETRY_JSONINSTRUMENTBUILDER_H_
-#define MANTID_NEXUSGEOMETRY_JSONINSTRUMENTBUILDER_H_
+#pragma once
 
 #include "MantidGeometry/Instrument_fwd.h"
 #include "MantidNexusGeometry/DllConfig.h"
@@ -36,5 +35,3 @@ private:
 
 } // namespace NexusGeometry
 } // namespace Mantid
-
-#endif /* MANTID_NEXUSGEOMETRY_JSONINSTRUMENTBUILDER_H_ */
diff --git a/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometryDefinitions.h b/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometryDefinitions.h
index 2c930988f566ef1da37c6d9dff475a3e801d2c7e..ce91a22b5df20022121c79d6a3a172d5cf195045 100644
--- a/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometryDefinitions.h
+++ b/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometryDefinitions.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTIDNEXUSGEOMETRY_NEXUSGEOMETRYDEFINITIONS_H
-#define MANTIDNEXUSGEOMETRY_NEXUSGEOMETRYDEFINITIONS_H
+#pragma once
 
 #include <H5Cpp.h>
 #include <string>
@@ -82,5 +81,3 @@ const std::string NEXUS_STRUCTURE = "nexus_structure";
 
 } // namespace NexusGeometry
 } // namespace Mantid
-
-#endif // MANTIDNEXUSGEOMETRY_NEXUSGEOMETRYDEFINITIONS_H
diff --git a/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometryParser.h b/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometryParser.h
index 8fa60dbd1700e9ecd6484eab973d328a4cc600d9..8a179a86f2acf4ea573521211645d06f5ae180c9 100644
--- a/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometryParser.h
+++ b/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometryParser.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTIDNEXUSGEOMETRY_PARSER_H_
-#define MANTIDNEXUSGEOMETRY_PARSER_H_
+#pragma once
 
 #include "MantidNexusGeometry/AbstractLogger.h"
 #include "MantidNexusGeometry/DllConfig.h"
@@ -30,5 +29,3 @@ getMangledName(const std::string &fileName, const std::string &instName);
 } // namespace NexusGeometryParser
 } // namespace NexusGeometry
 } // namespace Mantid
-
-#endif // MANTIDNEXUSGEOMETRY_PARSER_H_
diff --git a/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometrySave.h b/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometrySave.h
index 413e1da1058e4e0cd00cdc4d987ab3f9c07d0626..691f57d84db61665bcb3d35ef790723618f966fa 100644
--- a/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometrySave.h
+++ b/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometrySave.h
@@ -14,8 +14,7 @@
  * @date 07/08/2019
  */
 
-#ifndef MANTID_NEXUSGEOMETRY_NEXUSGEOMETRYSAVE_H_
-#define MANTID_NEXUSGEOMETRY_NEXUSGEOMETRYSAVE_H_
+#pragma once
 
 #include "MantidAPI/MatrixWorkspace.h"
 #include "MantidNexusGeometry/AbstractLogger.h"
@@ -67,5 +66,3 @@ MANTID_NEXUSGEOMETRY_DLL void saveInstrument(
 } // namespace NexusGeometrySave
 } // namespace NexusGeometry
 } // namespace Mantid
-
-#endif /* MANTID_NEXUSGEOMETRY_NEXUSGEOMETRYSAVE_H_ */
diff --git a/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometryUtilities.h b/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometryUtilities.h
index 0980441fe84545d1299954c0b63a9a1206b55adf..5dddb02af12fb4f0c53f3ed5e351b58634301172 100644
--- a/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometryUtilities.h
+++ b/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusGeometryUtilities.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_NEXUSGEOMETRY_NEXUSGEOMETRYUTILITIES_H_
-#define MANTID_NEXUSGEOMETRY_NEXUSGEOMETRYUTILITIES_H_
+#pragma once
 
 #include "MantidNexusGeometry/DllConfig.h"
 #include <H5Cpp.h>
@@ -45,5 +44,3 @@ bool isNamed(const H5::H5Object &obj, const std::string &name);
 } // namespace utilities
 } // namespace NexusGeometry
 } // namespace Mantid
-
-#endif /* MANTID_NEXUSGEOMETRY_NEXUSGEOMETRYUTILITIES_H_ */
diff --git a/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusShapeFactory.h b/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusShapeFactory.h
index 40286628be0690b632075c6cf94e8e4f1b079ca1..2d17eb50cb6610e7b96bd88fbfe98c368f519be9 100644
--- a/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusShapeFactory.h
+++ b/Framework/NexusGeometry/inc/MantidNexusGeometry/NexusShapeFactory.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTIDNEXUSGEOMETRY_SHAPEFACTORY_H
-#define MANTIDNEXUSGEOMETRY_SHAPEFACTORY_H
+#pragma once
 
 #include "MantidNexusGeometry/DllConfig.h"
 
@@ -55,5 +54,4 @@ createFromOFFMesh(const std::vector<uint32_t> &faceIndices,
                   const std::vector<Eigen::Vector3d> &nexusVertices);
 } // namespace NexusShapeFactory
 } // namespace NexusGeometry
-} // namespace Mantid
-#endif // MANTIDNEXUSGEOMETRY_SHAPEFACTORY_H
+} // namespace Mantid
\ No newline at end of file
diff --git a/Framework/NexusGeometry/inc/MantidNexusGeometry/TubeBuilder.h b/Framework/NexusGeometry/inc/MantidNexusGeometry/TubeBuilder.h
index 65e4a4292dff32e8175ff1b74f950ac80fd2fa35..44fb50c5d72285a31af07cb2bcf6817f31828aed 100644
--- a/Framework/NexusGeometry/inc/MantidNexusGeometry/TubeBuilder.h
+++ b/Framework/NexusGeometry/inc/MantidNexusGeometry/TubeBuilder.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTIDNEXUSGEOMETRY_TUBEBUILDER_H
-#define MANTIDNEXUSGEOMETRY_TUBEBUILDER_H
+#pragma once
 #include "MantidNexusGeometry/DllConfig.h"
 #include <Eigen/Core>
 #include <Eigen/Geometry>
@@ -56,5 +55,3 @@ private:
 } // namespace detail
 } // namespace NexusGeometry
 } // namespace Mantid
-
-#endif // MANTIDNEXUSGEOMETRY_TUBEBUILDER_H
diff --git a/Framework/NexusGeometry/inc/MantidNexusGeometry/TubeHelpers.h b/Framework/NexusGeometry/inc/MantidNexusGeometry/TubeHelpers.h
index 411b0ac64165215dd4efb5275ba994db0afa10f9..cd20d167873531e886178413f3c384de47b24bc2 100644
--- a/Framework/NexusGeometry/inc/MantidNexusGeometry/TubeHelpers.h
+++ b/Framework/NexusGeometry/inc/MantidNexusGeometry/TubeHelpers.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTIDNEXUSGEOMETRY_TUBEHELPERS_H
-#define MANTIDNEXUSGEOMETRY_TUBEHELPERS_H
+#pragma once
 
 #include "MantidGeometry/IDTypes.h"
 #include "MantidNexusGeometry/TubeBuilder.h"
@@ -32,5 +31,4 @@ notInTubes(const std::vector<detail::TubeBuilder> &tubes,
            std::vector<Mantid::detid_t> detIDs);
 } // namespace TubeHelpers
 } // namespace NexusGeometry
-} // namespace Mantid
-#endif // MANTIDNEXUSGEOMETRY_TUBEHELPER_H
+} // namespace Mantid
\ No newline at end of file
diff --git a/Framework/NexusGeometry/test/InstrumentBuilderTest.h b/Framework/NexusGeometry/test/InstrumentBuilderTest.h
index 19a67e57ae8ebb9c7815d3c1f37c7000f0a23c87..ce760753027d002660332235f65da14463b7d287 100644
--- a/Framework/NexusGeometry/test/InstrumentBuilderTest.h
+++ b/Framework/NexusGeometry/test/InstrumentBuilderTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef INSTRUMENT_GEOMETRY_ABSTRACTION_TEST_H_
-#define INSTRUMENT_GEOMETRY_ABSTRACTION_TEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -87,5 +86,3 @@ private:
   boost::shared_ptr<const Geometry::IObject> shape =
       boost::make_shared<const Geometry::CSGObject>();
 };
-
-#endif // INSTRUMENT_GEOMETRY_ABSTRACTION_TEST_H_
diff --git a/Framework/NexusGeometry/test/JSONGeometryParserTest.h b/Framework/NexusGeometry/test/JSONGeometryParserTest.h
index ecd2c614366637415aeb93e391a843ee4633099d..2d1e38e4a2113c32f4e836ac7b4169b572d70e43 100644
--- a/Framework/NexusGeometry/test/JSONGeometryParserTest.h
+++ b/Framework/NexusGeometry/test/JSONGeometryParserTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_NEXUSGEOMETRY_JSONGEOMETRYPARSERTEST_H_
-#define MANTID_NEXUSGEOMETRY_JSONGEOMETRYPARSERTEST_H_
+#pragma once
 
 #include "MantidKernel/ConfigService.h"
 #include "MantidKernel/Strings.h"
@@ -477,5 +476,3 @@ public:
 private:
   std::string instrument;
 };
-
-#endif /* MANTID_GEOMETRY_JSONGEOMETRYPARSERTEST_H_ */
diff --git a/Framework/NexusGeometry/test/JSONInstrumentBuilderTest.h b/Framework/NexusGeometry/test/JSONInstrumentBuilderTest.h
index b1371c7b4b52afb424a42ba660c38e7aee6d9ab6..a3fb7148a17913ac62f3177ea2c1fc856b333842 100644
--- a/Framework/NexusGeometry/test/JSONInstrumentBuilderTest.h
+++ b/Framework/NexusGeometry/test/JSONInstrumentBuilderTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_NEXUSGEOMETRY_JSONINSTRUMENTBUILDERTEST_H_
-#define MANTID_NEXUSGEOMETRY_JSONINSTRUMENTBUILDERTEST_H_
+#pragma once
 
 #include "MantidGeometry/Instrument.h"
 #include "MantidNexusGeometry/JSONGeometryParser.h"
@@ -61,5 +60,3 @@ public:
     TS_ASSERT_EQUALS(max_id, 90000); // monitor
   }
 };
-
-#endif /* MANTID_NEXUSGEOMETRY_JSONINSTRUMENTBUILDERTEST_H_ */
diff --git a/Framework/NexusGeometry/test/NexusGeometryParserTest.h b/Framework/NexusGeometry/test/NexusGeometryParserTest.h
index 319a3c1f9a15143f82e78f0dc1a0e94c882896a5..dba4a3efa189d4ee1b16393b795b56a5e24545ad 100644
--- a/Framework/NexusGeometry/test/NexusGeometryParserTest.h
+++ b/Framework/NexusGeometry/test/NexusGeometryParserTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef NEXUSGEOMETRYPARSERTEST_H_
-#define NEXUSGEOMETRYPARSERTEST_H_
+#pragma once
 
 #include <cxxtest/TestSuite.h>
 
@@ -391,5 +390,4 @@ private:
   std::string m_wishHDF5DefinitionPath;
   std::string m_sans2dHDF5DefinitionPath;
   std::string m_lokiHDF5DefinitionPath;
-};
-#endif
+};
\ No newline at end of file
diff --git a/Framework/NexusGeometry/test/NexusGeometrySaveTest.h b/Framework/NexusGeometry/test/NexusGeometrySaveTest.h
index 5c8fe184e854faddbb366c64f15b02abe5e3a0f0..cbd3a3d5f3264a9a1df403743dec183362d85acd 100644
--- a/Framework/NexusGeometry/test/NexusGeometrySaveTest.h
+++ b/Framework/NexusGeometry/test/NexusGeometrySaveTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef MANTID_NEXUSGEOMETRY_NEXUSGEOMETRYSAVETEST_H_
-#define MANTID_NEXUSGEOMETRY_NEXUSGEOMETRYSAVETEST_H_
+#pragma once
 
 #include "MantidGeometry/Instrument/ComponentInfo.h"
 #include "MantidGeometry/Instrument/ComponentInfoBankHelpers.h"
@@ -1163,5 +1162,3 @@ Instrument cache.
                      H5::GroupIException &);
   }
 };
-
-#endif /* MANTID_NEXUSGEOMETRY_NEXUSGEOMETRYSAVETEST_H_ */
diff --git a/Framework/NexusGeometry/test/TubeBuilderTest.h b/Framework/NexusGeometry/test/TubeBuilderTest.h
index b3b8e2e48a65339276f4f25c10a52603e8238c8c..490c4325639ae61bd851672da065933aabfbea2e 100644
--- a/Framework/NexusGeometry/test/TubeBuilderTest.h
+++ b/Framework/NexusGeometry/test/TubeBuilderTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef TUBE_TEST_H_
-#define TUBE_TEST_H_
+#pragma once
 
 #include "MantidGeometry/Objects/IObject.h"
 #include "MantidGeometry/Rendering/GeometryHandler.h"
@@ -68,5 +67,3 @@ public:
     TS_ASSERT_EQUALS(tube.size(), 1);
   }
 };
-
-#endif // TUBE_TEST_H_
diff --git a/Framework/NexusGeometry/test/TubeHelpersTest.h b/Framework/NexusGeometry/test/TubeHelpersTest.h
index 0ab747a63d75ee74764b126f81f355d15b173ae9..f6a68455d3373a9e88173ea684b500974561d815 100644
--- a/Framework/NexusGeometry/test/TubeHelpersTest.h
+++ b/Framework/NexusGeometry/test/TubeHelpersTest.h
@@ -4,8 +4,7 @@
 //     NScD Oak Ridge National Laboratory, European Spallation Source
 //     & Institut Laue - Langevin
 // SPDX - License - Identifier: GPL - 3.0 +
-#ifndef TUBEHELPERS_TEST_H_
-#define TUBEHELPERS_TEST_H_
+#pragma once
 
 #include "MantidGeometry/Objects/IObject.h"
 #include "MantidNexusGeometry/NexusShapeFactory.h"
@@ -81,5 +80,3 @@ public:
     TS_ASSERT_EQUALS(notInTubes[1], detIds[3]);
   }
 };
-
-#endif // TUBEHELPERS_TEST_H_
diff --git a/Framework/NexusGeometry/test/mockobjects.h b/Framework/NexusGeometry/test/mockobjects.h
index 02adc52e77289a66f8cb3e3634caea04a48c1ada..13be27d7e26ecc67dc40070a2e5ad247ada06e2b 100644
--- a/Framework/NexusGeometry/test/mockobjects.h
+++ b/Framework/NexusGeometry/test/mockobjects.h
@@ -1,5 +1,4 @@
-#ifndef NEXUSGEOMETRY_MOCKOBJECTS_H
-#define NEXUSGEOMETRY_MOCKOBJECTS_H
+#pragma once
 #include "MantidKernel/ProgressBase.h"
 #include "MantidKernel/WarningSuppressions.h"
 #include "MantidNexusGeometry/AbstractLogger.h"
@@ -19,5 +18,3 @@ public:
   MOCK_METHOD1(error, void(const std::string &));
   GNU_DIAG_ON_SUGGEST_OVERRIDE
 };
-
-#endif // NEXUSGEOMETRY_MOCKOBJECTS_H