diff --git a/libgimpbase/gimpchecks.h b/libgimpbase/gimpchecks.h
index 53e6e72911..fa02aa35a5 100644
--- a/libgimpbase/gimpchecks.h
+++ b/libgimpbase/gimpchecks.h
@@ -16,14 +16,16 @@
  * <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:
  *
@@ -137,4 +139,7 @@ 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 ee87079cfb..b1e53e3774 100644
--- a/libgimpbase/gimpchoice.h
+++ b/libgimpbase/gimpchoice.h
@@ -19,14 +19,17 @@
  * <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 */
 
 
@@ -85,4 +88,7 @@ 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 d5448c29b6..eb8cb044fe 100644
--- a/libgimpbase/gimpcompatenums.h
+++ b/libgimpbase/gimpcompatenums.h
@@ -16,7 +16,9 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#pragma once
+#ifndef __GIMP_COMPAT_ENUMS_H__
+#define __GIMP_COMPAT_ENUMS_H__
+
 
 G_BEGIN_DECLS
 
@@ -46,4 +48,7 @@ typedef enum /*< skip >*/
 } GimpAddMaskTypeCompat;
 #endif
 
+
 G_END_DECLS
+
+#endif  /* __GIMP_COMPAT_ENUMS_H__ */
diff --git a/libgimpbase/gimpcpuaccel.h b/libgimpbase/gimpcpuaccel.h
index 27ff4458ff..73495bd317 100644
--- a/libgimpbase/gimpcpuaccel.h
+++ b/libgimpbase/gimpcpuaccel.h
@@ -16,14 +16,16 @@
  * <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
@@ -64,4 +66,7 @@ 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 03d878e90d..fae7a86f4a 100644
--- a/libgimpbase/gimpenv-private.h
+++ b/libgimpbase/gimpenv-private.h
@@ -18,7 +18,8 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#pragma once
+#ifndef __GIMP_ENV_PRIVATE_H__
+#define __GIMP_ENV_PRIVATE_H__
 
 G_BEGIN_DECLS
 
@@ -27,4 +28,7 @@ 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 78a91977e8..e2eaad76e9 100644
--- a/libgimpbase/gimpenv.h
+++ b/libgimpbase/gimpenv.h
@@ -19,12 +19,13 @@
  * <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 */
@@ -76,4 +77,7 @@ 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 5be237d2f4..f8ddbc64f2 100644
--- a/libgimpbase/gimpexportoptions.h
+++ b/libgimpbase/gimpexportoptions.h
@@ -18,14 +18,17 @@
  * 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 */
 
 
@@ -34,6 +37,7 @@ G_BEGIN_DECLS
 G_DECLARE_FINAL_TYPE (GimpExportOptions, gimp_export_options, GIMP, EXPORT_OPTIONS, GObject)
 
 
+
 /*
  * GIMP_TYPE_PARAM_EXPORT_OPTIONS
  */
@@ -49,4 +53,7 @@ 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 d9bbe873a0..75a08b9fa7 100644
--- a/libgimpbase/gimplimits.h
+++ b/libgimpbase/gimplimits.h
@@ -19,14 +19,16 @@
  * <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
@@ -89,4 +91,7 @@ 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 4fd1aa49e9..cdfd9c0120 100644
--- a/libgimpbase/gimpmemsize.h
+++ b/libgimpbase/gimpmemsize.h
@@ -16,14 +16,16 @@
  * <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:
  *
@@ -57,4 +59,7 @@ 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 bb94cb71e4..57b41693fe 100644
--- a/libgimpbase/gimpmetadata.h
+++ b/libgimpbase/gimpmetadata.h
@@ -19,17 +19,16 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#pragma once
-
-#include <gexiv2/gexiv2.h>
+#ifndef __GIMP_METADATA_H__
+#define __GIMP_METADATA_H__
 
 G_BEGIN_DECLS
 
+#include <gexiv2/gexiv2.h>
+
+
 #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)
 
 
 /**
@@ -158,3 +157,5 @@ 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 7dd70b3e52..b920d5c0a1 100644
--- a/libgimpbase/gimpparamspecs.h
+++ b/libgimpbase/gimpparamspecs.h
@@ -18,12 +18,13 @@
  * <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 */
@@ -409,4 +410,7 @@ 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 b741a73c6d..f471976c18 100644
--- a/libgimpbase/gimpparasite.h
+++ b/libgimpbase/gimpparasite.h
@@ -19,12 +19,13 @@
  * <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 */
@@ -108,3 +109,5 @@ 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 2cc51d4de1..0ade6b44c8 100644
--- a/libgimpbase/gimpparasiteio.h
+++ b/libgimpbase/gimpparasiteio.h
@@ -19,7 +19,8 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#pragma once
+#ifndef __GIMP_PARASITE_IO_H__
+#define __GIMP_PARASITE_IO_H__
 
 G_BEGIN_DECLS
 
@@ -82,3 +83,5 @@ 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 8944805d9b..c9efb35294 100644
--- a/libgimpbase/gimpprotocol.h
+++ b/libgimpbase/gimpprotocol.h
@@ -16,7 +16,8 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#pragma once
+#ifndef __GIMP_PROTOCOL_H__
+#define __GIMP_PROTOCOL_H__
 
 G_BEGIN_DECLS
 
@@ -417,4 +418,7 @@ 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 3e8d6eff9b..8ace674df1 100644
--- a/libgimpbase/gimprectangle.h
+++ b/libgimpbase/gimprectangle.h
@@ -16,12 +16,13 @@
  * <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 */
@@ -53,4 +54,7 @@ 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 81ede8ff3d..a7af912d3c 100644
--- a/libgimpbase/gimpreloc.h
+++ b/libgimpbase/gimpreloc.h
@@ -10,10 +10,12 @@
  * more information and how to use this.
  */
 
-#pragma once
+#ifndef __GIMP_RELOC_H__
+#define __GIMP_RELOC_H__
 
 G_BEGIN_DECLS
 
+
 /* These error codes can be returned from _gimp_reloc_init() or
  * _gimp_reloc_init_lib().
  */
@@ -38,4 +40,7 @@ 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 6ed321621f..978a39408e 100644
--- a/libgimpbase/gimpsignal.h
+++ b/libgimpbase/gimpsignal.h
@@ -16,7 +16,8 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#pragma once
+#ifndef __GIMP_SIGNAL_H__
+#define __GIMP_SIGNAL_H__
 
 #include <signal.h>
 
@@ -37,9 +38,11 @@ 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 5ea4159e33..612e3150bd 100644
--- a/libgimpbase/gimputils.h
+++ b/libgimpbase/gimputils.h
@@ -16,14 +16,16 @@
  * <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,
@@ -90,3 +92,5 @@ 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 d13e16f094..b293e4f646 100644
--- a/libgimpbase/gimpvaluearray.h
+++ b/libgimpbase/gimpvaluearray.h
@@ -18,12 +18,13 @@
  * <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
 
 /**
@@ -96,4 +97,7 @@ 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 7865c415be..2f182da87d 100644
--- a/libgimpbase/gimpversion.h.in
+++ b/libgimpbase/gimpversion.h.in
@@ -1,4 +1,5 @@
-#pragma once
+#ifndef __GIMP_VERSION_H__
+#define __GIMP_VERSION_H__
 
 /* gimpversion.h.in -> gimpversion.h
  * This file is configured by Meson. Please modify meson.build files.
@@ -61,4 +62,7 @@ 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 eed5d13f28..45a3104a75 100644
--- a/libgimpbase/gimpwin32-io.h
+++ b/libgimpbase/gimpwin32-io.h
@@ -19,13 +19,15 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#pragma once
+#ifndef __GIMP_WIN32_IO_H__
+#define __GIMP_WIN32_IO_H__
 
 #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)
@@ -93,3 +95,5 @@ G_BEGIN_DECLS
 #endif
 
 G_END_DECLS
+
+#endif /* __GIMP_WIN32_IO_H__ */
diff --git a/libgimpbase/gimpwire.h b/libgimpbase/gimpwire.h
index 8237b20750..57f4c6c796 100644
--- a/libgimpbase/gimpwire.h
+++ b/libgimpbase/gimpwire.h
@@ -16,7 +16,8 @@
  * <https://www.gnu.org/licenses/>.
  */
 
-#pragma once
+#ifndef __GIMP_WIRE_H__
+#define __GIMP_WIRE_H__
 
 G_BEGIN_DECLS
 
@@ -145,4 +146,7 @@ G_GNUC_INTERNAL gboolean
                                                    gint            count,
                                                    gpointer        user_data);
 
+
 G_END_DECLS
+
+#endif /* __GIMP_WIRE_H__ */