diff --git a/libsgp4/CoordGeodetic.h b/libsgp4/CoordGeodetic.h
index 9b4127e..9dbb789 100644
--- a/libsgp4/CoordGeodetic.h
+++ b/libsgp4/CoordGeodetic.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef COORDGEODETIC_H_
-#define COORDGEODETIC_H_
+#pragma once
 
 #include "Util.h"
 
@@ -130,5 +129,3 @@ inline std::ostream& operator<<(std::ostream& strm, const CoordGeodetic& g)
 }
 
 } // namespace libsgp4
-
-#endif
diff --git a/libsgp4/CoordTopocentric.h b/libsgp4/CoordTopocentric.h
index c5a7fbb..8d9e2a9 100644
--- a/libsgp4/CoordTopocentric.h
+++ b/libsgp4/CoordTopocentric.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef COORDTOPOCENTRIC_H_
-#define COORDTOPOCENTRIC_H_
+#pragma once
 
 #include "Util.h"
 
@@ -127,5 +126,3 @@ inline std::ostream& operator<<(std::ostream& strm, const CoordTopocentric& t)
 }
 
 } // namespace libsgp4
-
-#endif
diff --git a/libsgp4/DateTime.h b/libsgp4/DateTime.h
index f3d81f0..68982d9 100644
--- a/libsgp4/DateTime.h
+++ b/libsgp4/DateTime.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef DATETIME_H_
-#define DATETIME_H_
+#pragma once
 
 #include <iomanip>
 #include <iostream>
@@ -720,5 +719,3 @@ inline bool operator<=(const DateTime& dt1, const DateTime& dt2)
 }
 
 } // namespace libsgp4
-
-#endif
diff --git a/libsgp4/DecayedException.h b/libsgp4/DecayedException.h
index 275e8c1..b05d350 100644
--- a/libsgp4/DecayedException.h
+++ b/libsgp4/DecayedException.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef DECAYEDEXCEPTION_H_
-#define DECAYEDEXCEPTION_H_
+#pragma once
 
 #include "DateTime.h"
 #include "Vector.h"
@@ -78,5 +77,3 @@ private:
 };
 
 } // namespace libsgp4
-
-#endif
diff --git a/libsgp4/Eci.h b/libsgp4/Eci.h
index 550733d..7a8197e 100644
--- a/libsgp4/Eci.h
+++ b/libsgp4/Eci.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef ECI_H_
-#define ECI_H_
+#pragma once
 
 #include "CoordGeodetic.h"
 #include "Vector.h"
@@ -145,5 +144,3 @@ private:
 };
 
 } // namespace libsgp4
-
-#endif
diff --git a/libsgp4/Globals.h b/libsgp4/Globals.h
index cec3157..cfc3d0a 100644
--- a/libsgp4/Globals.h
+++ b/libsgp4/Globals.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef GLOBALS_H_
-#define GLOBALS_H_
+#pragma once
 
 #include <cmath>
 
@@ -76,5 +75,3 @@ const double kHOURS_PER_DAY = 24.0;
 const double kA3OVK2 = -kXJ3 / kCK2 * kAE * kAE * kAE;
 
 } // namespace libsgp4
-
-#endif
diff --git a/libsgp4/Observer.h b/libsgp4/Observer.h
index 8f67210..df889f7 100644
--- a/libsgp4/Observer.h
+++ b/libsgp4/Observer.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef OBSERVER_H_
-#define OBSERVER_H_
+#pragma once
 
 #include "CoordGeodetic.h"
 #include "Eci.h"
@@ -102,5 +101,3 @@ private:
 };
 
 } // namespace libsgp4
-
-#endif
diff --git a/libsgp4/OrbitalElements.h b/libsgp4/OrbitalElements.h
index baf51ec..4b7847d 100644
--- a/libsgp4/OrbitalElements.h
+++ b/libsgp4/OrbitalElements.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef ORBITALELEMENTS_H_
-#define ORBITALELEMENTS_H_
+#pragma once
 
 #include "Util.h"
 #include "DateTime.h"
@@ -146,5 +145,3 @@ private:
 };
 
 } // namespace libsgp4
-
-#endif
diff --git a/libsgp4/SGP4.h b/libsgp4/SGP4.h
index 9485143..274d393 100644
--- a/libsgp4/SGP4.h
+++ b/libsgp4/SGP4.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef SGP4_H_
-#define SGP4_H_
+#pragma once
 
 #include "Tle.h"
 #include "OrbitalElements.h"
@@ -259,5 +258,3 @@ private:
 };
 
 } // namespace libsgp4
-
-#endif
diff --git a/libsgp4/SatelliteException.h b/libsgp4/SatelliteException.h
index ba4a081..0905b04 100644
--- a/libsgp4/SatelliteException.h
+++ b/libsgp4/SatelliteException.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef SATELLITEEXCEPTION_H_
-#define SATELLITEEXCEPTION_H_
+#pragma once
 
 #include <stdexcept>
 #include <string>
@@ -37,5 +36,3 @@ public:
 };
 
 } // namespace libsgp4
-
-#endif
diff --git a/libsgp4/SolarPosition.h b/libsgp4/SolarPosition.h
index 050f83f..c8cb105 100644
--- a/libsgp4/SolarPosition.h
+++ b/libsgp4/SolarPosition.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef SOLARPOSITION_H_
-#define SOLARPOSITION_H_
+#pragma once
 
 #include "DateTime.h"
 #include "Eci.h"
@@ -41,5 +40,3 @@ private:
 };
 
 } // namespace libsgp4
-
-#endif
diff --git a/libsgp4/TimeSpan.h b/libsgp4/TimeSpan.h
index 742432a..5190182 100644
--- a/libsgp4/TimeSpan.h
+++ b/libsgp4/TimeSpan.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef TIMESPAN_H_
-#define TIMESPAN_H_
+#pragma once
 
 #include <iostream>
 #include <sstream>
@@ -207,7 +206,7 @@ private:
             int microseconds)
     {
         m_ticks = days * TicksPerDay +
-            (hours * 3600LL + minutes * 60LL + seconds) * TicksPerSecond + 
+            (hours * 3600LL + minutes * 60LL + seconds) * TicksPerSecond +
             microseconds * TicksPerMicrosecond;
     }
 };
@@ -258,5 +257,3 @@ inline bool operator<=(const TimeSpan& ts1, const TimeSpan& ts2)
 }
 
 } // namespace libsgp4
-
-#endif
diff --git a/libsgp4/Tle.h b/libsgp4/Tle.h
index db46842..b39dd63 100644
--- a/libsgp4/Tle.h
+++ b/libsgp4/Tle.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef TLE_H_
-#define TLE_H_
+#pragma once
 
 #include "Util.h"
 #include "DateTime.h"
@@ -343,5 +342,3 @@ inline std::ostream& operator<<(std::ostream& strm, const Tle& t)
 }
 
 } // namespace libsgp4
-
-#endif
diff --git a/libsgp4/TleException.h b/libsgp4/TleException.h
index 4c75b44..ba5f39f 100644
--- a/libsgp4/TleException.h
+++ b/libsgp4/TleException.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef TLEEXCEPTION_H_
-#define TLEEXCEPTION_H_
+#pragma once
 
 #include <stdexcept>
 #include <string>
@@ -43,5 +42,3 @@ public:
 };
 
 } // namespace libsgp4
-
-#endif
diff --git a/libsgp4/Util.h b/libsgp4/Util.h
index 57ec650..4135a7d 100644
--- a/libsgp4/Util.h
+++ b/libsgp4/Util.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef UTIL_H_
-#define UTIL_H_
+#pragma once
 
 #include "Globals.h"
 
@@ -110,5 +109,3 @@ namespace Util
 
 } // namespace Util
 } // namespace libsgp4
-
-#endif
diff --git a/libsgp4/Vector.h b/libsgp4/Vector.h
index c50de56..5129129 100644
--- a/libsgp4/Vector.h
+++ b/libsgp4/Vector.h
@@ -15,8 +15,7 @@
  */
 
 
-#ifndef VECTOR_H_
-#define VECTOR_H_
+#pragma once
 
 #include <cmath>
 #include <string>
@@ -162,5 +161,3 @@ inline std::ostream& operator<<(std::ostream& strm, const Vector& v)
 }
 
 } // namespace libsgp4
-
-#endif