diff --git a/libgimpmath/gimpmath.h b/libgimpmath/gimpmath.h
index 346b3a08e3..4f08a5bdf7 100644
--- a/libgimpmath/gimpmath.h
+++ b/libgimpmath/gimpmath.h
@@ -18,9 +18,7 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#ifndef __GIMP_MATH_H__
-#define __GIMP_MATH_H__
-
+#pragma once
 
 #include <math.h>
 
@@ -41,10 +39,8 @@
 
 #undef __GIMP_MATH_H_INSIDE__
 
-
 G_BEGIN_DECLS
 
-
 /**
  * SECTION: gimpmath
  * @title: GimpMath
@@ -146,7 +142,4 @@ G_BEGIN_DECLS
  **/
 #define gimp_rad_to_deg(angle) ((angle) * 360.0 / (2.0 * G_PI))
 
-
 G_END_DECLS
-
-#endif /* __GIMP_MATH_H__ */
diff --git a/libgimpmath/gimpmathtypes.h b/libgimpmath/gimpmathtypes.h
index 559f883047..e5c444a5c6 100644
--- a/libgimpmath/gimpmathtypes.h
+++ b/libgimpmath/gimpmathtypes.h
@@ -18,13 +18,10 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#ifndef __GIMP_MATH_TYPES_H__
-#define __GIMP_MATH_TYPES_H__
-
+#pragma once
 
 #include <libgimpbase/gimpbasetypes.h>
 
-
 G_BEGIN_DECLS
 
 typedef struct _GimpMatrix2 GimpMatrix2;
@@ -128,7 +125,4 @@ struct _GimpVector4
   gdouble x, y, z, w;
 };
 
-
 G_END_DECLS
-
-#endif /* __GIMP_MATH_TYPES_H__ */
diff --git a/libgimpmath/gimpmatrix.h b/libgimpmath/gimpmatrix.h
index d0cc6fca95..59287a7086 100644
--- a/libgimpmath/gimpmatrix.h
+++ b/libgimpmath/gimpmatrix.h
@@ -19,13 +19,12 @@
  * <https://www.gnu.org/licenses/>.
  */
 
+#pragma once
+
 #if !defined (__GIMP_MATH_H_INSIDE__) && !defined (GIMP_MATH_COMPILATION)
 #error "Only <libgimpmath/gimpmath.h> can be included directly."
 #endif
 
-#ifndef __GIMP_MATRIX_H__
-#define __GIMP_MATRIX_H__
-
 G_BEGIN_DECLS
 
 /* For information look into the C source or the html documentation */
@@ -151,7 +150,4 @@ gdouble       gimp_matrix4_transform_point (const GimpMatrix4 *matrix,
                                             gdouble           *newy,
                                             gdouble           *newz);
 
-
 G_END_DECLS
-
-#endif /* __GIMP_MATRIX_H__ */
diff --git a/libgimpmath/gimpvector.h b/libgimpmath/gimpvector.h
index 77230dad1e..8f6a65f0dd 100644
--- a/libgimpmath/gimpvector.h
+++ b/libgimpmath/gimpvector.h
@@ -22,13 +22,12 @@
  * <https://www.gnu.org/licenses/>.
  */
 
+#pragma once
+
 #if !defined (__GIMP_MATH_H_INSIDE__) && !defined (GIMP_MATH_COMPILATION)
 #error "Only <libgimpmath/gimpmath.h> can be included directly."
 #endif
 
-#ifndef __GIMP_VECTOR_H__
-#define __GIMP_VECTOR_H__
-
 G_BEGIN_DECLS
 
 /* For information look into the C source or the html documentation */
@@ -154,7 +153,4 @@ void        gimp_vector_3d_to_2d           (gint               sx,
                                             const GimpVector3 *vp,
                                             const GimpVector3 *p);
 
-
 G_END_DECLS
-
-#endif  /* __GIMP_VECTOR_H__ */