diff --git a/libgimpbase/gimpchecks.h b/libgimpbase/gimpchecks.h
index fa02aa35a5..53e6e72911 100644
--- a/libgimpbase/gimpchecks.h
+++ b/libgimpbase/gimpchecks.h
@@ -16,16 +16,14 @@
  * <https://www.gnu.org/licenses/>.
  */
 
+#pragma once
+
 #if !defined (__GIMP_BASE_H_INSIDE__) && !defined (GIMP_BASE_COMPILATION)
 #error "Only <libgimpbase/gimpbase.h> can be included directly."
 #endif
 
-#ifndef __GIMP_CHECKS_H__
-#define __GIMP_CHECKS_H__
-
 G_BEGIN_DECLS
 
-
 /**
  * GIMP_CHECK_SIZE:
  *
@@ -139,7 +137,4 @@ void  gimp_checks_get_colors (GimpCheckType  type,
                               GeglColor     **color1,
                               GeglColor     **color2);
 
-
 G_END_DECLS
-
-#endif  /* __GIMP_CHECKS_H__ */
diff --git a/libgimpbase/gimpchoice.h b/libgimpbase/gimpchoice.h
index b1e53e3774..ee87079cfb 100644
--- a/libgimpbase/gimpchoice.h
+++ b/libgimpbase/gimpchoice.h
@@ -19,17 +19,14 @@
  * <https://www.gnu.org/licenses/>.
  */
 
+#pragma once
+
 #if !defined (__GIMP_BASE_H_INSIDE__) && !defined (GIMP_BASE_COMPILATION)
 #error "Only <libgimpbase/gimpbase.h> can be included directly."
 #endif
 
-
-#ifndef __GIMP_CHOICE_H__
-#define __GIMP_CHOICE_H__
-
 G_BEGIN_DECLS
 
-
 /* For information look into the C source or the html documentation */
 
 
@@ -88,7 +85,4 @@ GParamSpec * gimp_param_spec_choice             (const gchar  *name,
 GimpChoice  * gimp_param_spec_choice_get_choice  (GParamSpec *pspec);
 const gchar * gimp_param_spec_choice_get_default (GParamSpec *pspec);
 
-
 G_END_DECLS
-
-#endif /* __GIMP_CHOICE_H__ */
diff --git a/libgimpbase/gimpcompatenums.h b/libgimpbase/gimpcompatenums.h
index eb8cb044fe..d5448c29b6 100644
--- a/libgimpbase/gimpcompatenums.h
+++ b/libgimpbase/gimpcompatenums.h
@@ -16,9 +16,7 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#ifndef __GIMP_COMPAT_ENUMS_H__
-#define __GIMP_COMPAT_ENUMS_H__
-
+#pragma once
 
 G_BEGIN_DECLS
 
@@ -48,7 +46,4 @@ typedef enum /*< skip >*/
 } GimpAddMaskTypeCompat;
 #endif
 
-
 G_END_DECLS
-
-#endif  /* __GIMP_COMPAT_ENUMS_H__ */
diff --git a/libgimpbase/gimpcpuaccel.h b/libgimpbase/gimpcpuaccel.h
index 73495bd317..27ff4458ff 100644
--- a/libgimpbase/gimpcpuaccel.h
+++ b/libgimpbase/gimpcpuaccel.h
@@ -16,16 +16,14 @@
  * <https://www.gnu.org/licenses/>.
  */
 
+#pragma once
+
 #if !defined (__GIMP_BASE_H_INSIDE__) && !defined (GIMP_BASE_COMPILATION)
 #error "Only <libgimpbase/gimpbase.h> can be included directly."
 #endif
 
-#ifndef __GIMP_CPU_ACCEL_H__
-#define __GIMP_CPU_ACCEL_H__
-
 G_BEGIN_DECLS
 
-
 /**
  * GimpCpuAccelFlags:
  * @GIMP_CPU_ACCEL_NONE:        None
@@ -66,7 +64,4 @@ typedef enum
 
 GimpCpuAccelFlags  gimp_cpu_accel_get_support (void);
 
-
 G_END_DECLS
-
-#endif  /* __GIMP_CPU_ACCEL_H__ */
diff --git a/libgimpbase/gimpenv-private.h b/libgimpbase/gimpenv-private.h
index fae7a86f4a..03d878e90d 100644
--- a/libgimpbase/gimpenv-private.h
+++ b/libgimpbase/gimpenv-private.h
@@ -18,8 +18,7 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#ifndef __GIMP_ENV_PRIVATE_H__
-#define __GIMP_ENV_PRIVATE_H__
+#pragma once
 
 G_BEGIN_DECLS
 
@@ -28,7 +27,4 @@ G_BEGIN_DECLS
 
 void          gimp_env_init                    (gboolean      plug_in);
 
-
 G_END_DECLS
-
-#endif  /*  __GIMP_ENV_PRIVATE_H__  */
diff --git a/libgimpbase/gimpenv.h b/libgimpbase/gimpenv.h
index e2eaad76e9..78a91977e8 100644
--- a/libgimpbase/gimpenv.h
+++ b/libgimpbase/gimpenv.h
@@ -19,13 +19,12 @@
  * <https://www.gnu.org/licenses/>.
  */
 
+#pragma once
+
 #if !defined (__GIMP_BASE_H_INSIDE__) && !defined (GIMP_BASE_COMPILATION)
 #error "Only <libgimpbase/gimpbase.h> can be included directly."
 #endif
 
-#ifndef __GIMP_ENV_H__
-#define __GIMP_ENV_H__
-
 G_BEGIN_DECLS
 
 /* For information look into the C source or the html documentation */
@@ -77,7 +76,4 @@ void          gimp_path_free                   (GList        *path);
 
 gchar       * gimp_path_get_user_writable_dir  (GList        *path) G_GNUC_MALLOC;
 
-
 G_END_DECLS
-
-#endif  /*  __GIMP_ENV_H__  */
diff --git a/libgimpbase/gimpexportoptions.h b/libgimpbase/gimpexportoptions.h
index f8ddbc64f2..5be237d2f4 100644
--- a/libgimpbase/gimpexportoptions.h
+++ b/libgimpbase/gimpexportoptions.h
@@ -18,17 +18,14 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+#pragma once
+
 #if !defined (__GIMP_BASE_H_INSIDE__) && !defined (GIMP_BASE_COMPILATION)
 #error "Only <libgimpbase/gimpbase.h> can be included directly."
 #endif
 
-
-#ifndef __GIMP_EXPORT_OPTIONS_H__
-#define __GIMP_EXPORT_OPTIONS_H__
-
 G_BEGIN_DECLS
 
-
 /* For information look into the C source or the html documentation */
 
 
@@ -37,7 +34,6 @@ G_BEGIN_DECLS
 G_DECLARE_FINAL_TYPE (GimpExportOptions, gimp_export_options, GIMP, EXPORT_OPTIONS, GObject)
 
 
-
 /*
  * GIMP_TYPE_PARAM_EXPORT_OPTIONS
  */
@@ -53,7 +49,4 @@ GParamSpec * gimp_param_spec_export_options     (const gchar  *name,
                                                  const gchar  *blurb,
                                                  GParamFlags   flags);
 
-
 G_END_DECLS
-
-#endif /* __GIMP_EXPORT_OPTIONS_H__ */
diff --git a/libgimpbase/gimplimits.h b/libgimpbase/gimplimits.h
index 75a08b9fa7..d9bbe873a0 100644
--- a/libgimpbase/gimplimits.h
+++ b/libgimpbase/gimplimits.h
@@ -19,16 +19,14 @@
  * <https://www.gnu.org/licenses/>.
  */
 
+#pragma once
+
 #if !defined (__GIMP_BASE_H_INSIDE__) && !defined (GIMP_BASE_COMPILATION)
 #error "Only <libgimpbase/gimpbase.h> can be included directly."
 #endif
 
-#ifndef __GIMP_LIMITS_H__
-#define __GIMP_LIMITS_H__
-
 G_BEGIN_DECLS
 
-
 /**
  * SECTION: gimplimits
  * @title: gimplimits
@@ -91,7 +89,4 @@ G_BEGIN_DECLS
                                                   *  and must be < G_MAXDOUBLE
                                                   */
 
-
 G_END_DECLS
-
-#endif /* __GIMP_LIMITS_H__ */
diff --git a/libgimpbase/gimpmemsize.h b/libgimpbase/gimpmemsize.h
index cdfd9c0120..4fd1aa49e9 100644
--- a/libgimpbase/gimpmemsize.h
+++ b/libgimpbase/gimpmemsize.h
@@ -16,16 +16,14 @@
  * <https://www.gnu.org/licenses/>.
  */
 
+#pragma once
+
 #if !defined (__GIMP_BASE_H_INSIDE__) && !defined (GIMP_BASE_COMPILATION)
 #error "Only <libgimpbase/gimpbase.h> can be included directly."
 #endif
 
-#ifndef __GIMP_MEMSIZE_H__
-#define __GIMP_MEMSIZE_H__
-
 G_BEGIN_DECLS
 
-
 /**
  * GIMP_TYPE_MEMSIZE:
  *
@@ -59,7 +57,4 @@ GParamSpec * gimp_param_spec_memsize      (const gchar  *name,
                                            guint64       default_value,
                                            GParamFlags   flags);
 
-
 G_END_DECLS
-
-#endif  /* __GIMP_MEMSIZE_H__ */
diff --git a/libgimpbase/gimpmetadata.h b/libgimpbase/gimpmetadata.h
index 8f7b028612..02860c907b 100644
--- a/libgimpbase/gimpmetadata.h
+++ b/libgimpbase/gimpmetadata.h
@@ -19,16 +19,17 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#ifndef __GIMP_METADATA_H__
-#define __GIMP_METADATA_H__
-
-G_BEGIN_DECLS
+#pragma once
 
 #include <gexiv2/gexiv2.h>
 
+G_BEGIN_DECLS
 
 #define GIMP_TYPE_METADATA (gimp_metadata_get_type ())
-G_DECLARE_FINAL_TYPE (GimpMetadata, gimp_metadata, GIMP, METADATA, GExiv2Metadata)
+G_DECLARE_FINAL_TYPE (GimpMetadata,
+                      gimp_metadata,
+                      GIMP, METADATA,
+                      GExiv2Metadata)
 
 
 /**
@@ -154,5 +155,3 @@ gboolean       gimp_metadata_is_tag_supported    (const gchar            *tag,
                                                   const gchar            *mime_type);
 
 G_END_DECLS
-
-#endif /* __GIMP_METADATA_H__ */
diff --git a/libgimpbase/gimpparamspecs.h b/libgimpbase/gimpparamspecs.h
index b920d5c0a1..7dd70b3e52 100644
--- a/libgimpbase/gimpparamspecs.h
+++ b/libgimpbase/gimpparamspecs.h
@@ -18,13 +18,12 @@
  * <https://www.gnu.org/licenses/>.
  */
 
+#pragma once
+
 #if !defined (__GIMP_BASE_H_INSIDE__) && !defined (GIMP_BASE_COMPILATION)
 #error "Only <libgimpbase/gimpbase.h> can be included directly."
 #endif
 
-#ifndef __GIMP_PARAM_SPECS_H__
-#define __GIMP_PARAM_SPECS_H__
-
 G_BEGIN_DECLS
 
 /* For information look into the C source or the html documentation */
@@ -410,7 +409,4 @@ GParamSpec  * gimp_param_spec_core_object_array                 (const gchar   *
 
 GType         gimp_param_spec_core_object_array_get_object_type (GParamSpec *pspec);
 
-
 G_END_DECLS
-
-#endif  /*  __GIMP_PARAM_SPECS_H__  */
diff --git a/libgimpbase/gimpparasite.h b/libgimpbase/gimpparasite.h
index f471976c18..b741a73c6d 100644
--- a/libgimpbase/gimpparasite.h
+++ b/libgimpbase/gimpparasite.h
@@ -19,13 +19,12 @@
  * <https://www.gnu.org/licenses/>.
  */
 
+#pragma once
+
 #if !defined (__GIMP_BASE_H_INSIDE__) && !defined (GIMP_BASE_COMPILATION)
 #error "Only <libgimpbase/gimpbase.h> can be included directly."
 #endif
 
-#ifndef __GIMP_PARASITE_H__
-#define __GIMP_PARASITE_H__
-
 G_BEGIN_DECLS
 
 /* For information look into the C source or the html documentation */
@@ -109,5 +108,3 @@ gconstpointer  gimp_parasite_get_data      (const GimpParasite *parasite,
                                             guint32            *num_bytes);
 
 G_END_DECLS
-
-#endif /* __GIMP_PARASITE_H__ */
diff --git a/libgimpbase/gimpparasiteio.h b/libgimpbase/gimpparasiteio.h
index 0ade6b44c8..2cc51d4de1 100644
--- a/libgimpbase/gimpparasiteio.h
+++ b/libgimpbase/gimpparasiteio.h
@@ -19,8 +19,7 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#ifndef __GIMP_PARASITE_IO_H__
-#define __GIMP_PARASITE_IO_H__
+#pragma once
 
 G_BEGIN_DECLS
 
@@ -83,5 +82,3 @@ gchar * gimp_pixpipe_params_build (GimpPixPipeParams *params) G_GNUC_MALLOC;
 void    gimp_pixpipe_params_free  (GimpPixPipeParams *params);
 
 G_END_DECLS
-
-#endif /* __GIMP_PARASITE_IO_H__ */
diff --git a/libgimpbase/gimpprotocol.h b/libgimpbase/gimpprotocol.h
index 0fccb5b42f..c5427991f5 100644
--- a/libgimpbase/gimpprotocol.h
+++ b/libgimpbase/gimpprotocol.h
@@ -16,8 +16,7 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#ifndef __GIMP_PROTOCOL_H__
-#define __GIMP_PROTOCOL_H__
+#pragma once
 
 G_BEGIN_DECLS
 
@@ -417,7 +416,4 @@ gboolean  gp_extension_ack_write    (GIOChannel      *channel,
 gboolean  gp_has_init_write         (GIOChannel      *channel,
                                      gpointer         user_data);
 
-
 G_END_DECLS
-
-#endif /* __GIMP_PROTOCOL_H__ */
diff --git a/libgimpbase/gimprectangle.h b/libgimpbase/gimprectangle.h
index 8ace674df1..3e8d6eff9b 100644
--- a/libgimpbase/gimprectangle.h
+++ b/libgimpbase/gimprectangle.h
@@ -16,13 +16,12 @@
  * <https://www.gnu.org/licenses/>.
  */
 
+#pragma once
+
 #if !defined (__GIMP_BASE_H_INSIDE__) && !defined (GIMP_BASE_COMPILATION)
 #error "Only <libgimpbase/gimpbase.h> can be included directly."
 #endif
 
-#ifndef __GIMP_RECTANGLE_H__
-#define __GIMP_RECTANGLE_H__
-
 G_BEGIN_DECLS
 
 /* For information look into the C source or the html documentation */
@@ -54,7 +53,4 @@ void      gimp_rectangle_union     (gint  x1,
                                     gint *dest_width,
                                     gint *dest_height);
 
-
 G_END_DECLS
-
-#endif  /* __GIMP_RECTANGLE_H__ */
diff --git a/libgimpbase/gimpreloc.h b/libgimpbase/gimpreloc.h
index a7af912d3c..81ede8ff3d 100644
--- a/libgimpbase/gimpreloc.h
+++ b/libgimpbase/gimpreloc.h
@@ -10,12 +10,10 @@
  * more information and how to use this.
  */
 
-#ifndef __GIMP_RELOC_H__
-#define __GIMP_RELOC_H__
+#pragma once
 
 G_BEGIN_DECLS
 
-
 /* These error codes can be returned from _gimp_reloc_init() or
  * _gimp_reloc_init_lib().
  */
@@ -40,7 +38,4 @@ G_GNUC_INTERNAL gboolean _gimp_reloc_init_lib    (GError **error);
 
 G_GNUC_INTERNAL gchar  * _gimp_reloc_find_prefix (const gchar *default_prefix);
 
-
 G_END_DECLS
-
-#endif /* _GIMPRELOC_H_ */
diff --git a/libgimpbase/gimpsignal.h b/libgimpbase/gimpsignal.h
index 978a39408e..6ed321621f 100644
--- a/libgimpbase/gimpsignal.h
+++ b/libgimpbase/gimpsignal.h
@@ -16,8 +16,7 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#ifndef __GIMP_SIGNAL_H__
-#define __GIMP_SIGNAL_H__
+#pragma once
 
 #include <signal.h>
 
@@ -38,11 +37,9 @@ G_BEGIN_DECLS
  **/
 typedef void (* GimpSignalHandlerFunc) (gint signum);
 
+
 GimpSignalHandlerFunc  gimp_signal_private (gint                   signum,
                                             GimpSignalHandlerFunc  handler,
                                             gint                   flags);
 
-
 G_END_DECLS
-
-#endif /* __GIMP_SIGNAL_H__ */
diff --git a/libgimpbase/gimputils.h b/libgimpbase/gimputils.h
index 612e3150bd..5ea4159e33 100644
--- a/libgimpbase/gimputils.h
+++ b/libgimpbase/gimputils.h
@@ -16,16 +16,14 @@
  * <https://www.gnu.org/licenses/>.
  */
 
+#pragma once
+
 #if !defined (__GIMP_BASE_H_INSIDE__) && !defined (GIMP_BASE_COMPILATION)
 #error "Only <libgimpbase/gimpbase.h> can be included directly."
 #endif
 
-#ifndef __GIMP_UTILS_H__
-#define __GIMP_UTILS_H__
-
 G_BEGIN_DECLS
 
-
 gchar               * gimp_utf8_strtrim              (const gchar       *str,
                                                       gint               max_chars) G_GNUC_MALLOC;
 gchar               * gimp_any_to_utf8               (const gchar       *str,
@@ -92,5 +90,3 @@ void                  gimp_bind_text_domain          (const gchar       *domain_
                                                       const gchar       *dir_name);
 
 G_END_DECLS
-
-#endif  /* __GIMP_UTILS_H__ */
diff --git a/libgimpbase/gimpvaluearray.h b/libgimpbase/gimpvaluearray.h
index b293e4f646..d13e16f094 100644
--- a/libgimpbase/gimpvaluearray.h
+++ b/libgimpbase/gimpvaluearray.h
@@ -18,13 +18,12 @@
  * <https://www.gnu.org/licenses/>.
  */
 
+#pragma once
+
 #if !defined (__GIMP_BASE_H_INSIDE__) && !defined (GIMP_BASE_COMPILATION)
 #error "Only <libgimpbase/gimpbase.h> can be included directly."
 #endif
 
-#ifndef __GIMP_VALUE_ARRAY_H__
-#define __GIMP_VALUE_ARRAY_H__
-
 G_BEGIN_DECLS
 
 /**
@@ -97,7 +96,4 @@ GParamSpec * gimp_param_spec_value_array                  (const gchar    *name,
 
 GParamSpec * gimp_param_spec_value_array_get_element_spec (GParamSpec *pspec);
 
-
 G_END_DECLS
-
-#endif /* __GIMP_VALUE_ARRAY_H__ */
diff --git a/libgimpbase/gimpversion.h.in b/libgimpbase/gimpversion.h.in
index 2f182da87d..7865c415be 100644
--- a/libgimpbase/gimpversion.h.in
+++ b/libgimpbase/gimpversion.h.in
@@ -1,5 +1,4 @@
-#ifndef __GIMP_VERSION_H__
-#define __GIMP_VERSION_H__
+#pragma once
 
 /* gimpversion.h.in -> gimpversion.h
  * This file is configured by Meson. Please modify meson.build files.
@@ -62,7 +61,4 @@ G_BEGIN_DECLS
      (GIMP_MAJOR_VERSION == (major) && GIMP_MINOR_VERSION == (minor) && \
       GIMP_MICRO_VERSION >= (micro)))
 
-
 G_END_DECLS
-
-#endif /* __GIMP_VERSION_H__ */
diff --git a/libgimpbase/gimpwin32-io.h b/libgimpbase/gimpwin32-io.h
index 45a3104a75..eed5d13f28 100644
--- a/libgimpbase/gimpwin32-io.h
+++ b/libgimpbase/gimpwin32-io.h
@@ -19,15 +19,13 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#ifndef __GIMP_WIN32_IO_H__
-#define __GIMP_WIN32_IO_H__
+#pragma once
 
 #include <io.h>
 #include <direct.h>
 
 G_BEGIN_DECLS
 
-
 #define mkdir(n,a)  _mkdir(n)
 #define chmod(n,f)  _chmod(n,f)
 #define access(f,p) _access(f,p)
@@ -95,5 +93,3 @@ G_BEGIN_DECLS
 #endif
 
 G_END_DECLS
-
-#endif /* __GIMP_WIN32_IO_H__ */
diff --git a/libgimpbase/gimpwire.h b/libgimpbase/gimpwire.h
index 57f4c6c796..8237b20750 100644
--- a/libgimpbase/gimpwire.h
+++ b/libgimpbase/gimpwire.h
@@ -16,8 +16,7 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#ifndef __GIMP_WIRE_H__
-#define __GIMP_WIRE_H__
+#pragma once
 
 G_BEGIN_DECLS
 
@@ -146,7 +145,4 @@ G_GNUC_INTERNAL gboolean
                                                    gint            count,
                                                    gpointer        user_data);
 
-
 G_END_DECLS
-
-#endif /* __GIMP_WIRE_H__ */