diff --git a/demos/gtk-demo/fontplane.c b/demos/gtk-demo/fontplane.c
index 038ae68f58..f3bf5a4394 100644
--- a/demos/gtk-demo/fontplane.c
+++ b/demos/gtk-demo/fontplane.c
@@ -276,7 +276,7 @@ gtk_font_plane_class_init (GtkFontPlaneClass *class)
 
 GtkWidget *
 gtk_font_plane_new (GtkAdjustment *weight_adj,
-                     GtkAdjustment *width_adj)
+                    GtkAdjustment *width_adj)
 {
   return g_object_new (GTK_TYPE_FONT_PLANE,
                        "weight-adjustment", weight_adj,
diff --git a/demos/gtk-demo/fontplane.h b/demos/gtk-demo/fontplane.h
index 94187db744..d684f9609b 100644
--- a/demos/gtk-demo/fontplane.h
+++ b/demos/gtk-demo/fontplane.h
@@ -55,7 +55,7 @@ struct _GtkFontPlaneClass
 
 
 GType       gtk_font_plane_get_type (void) G_GNUC_CONST;
-GtkWidget * gtk_font_plane_new      (GtkAdjustment *width_adj,
-                                     GtkAdjustment *weight_adj);
+GtkWidget * gtk_font_plane_new      (GtkAdjustment *weight_adj,
+                                     GtkAdjustment *width_adj);
 
 G_END_DECLS
diff --git a/demos/gtk-demo/gtkfishbowl.h b/demos/gtk-demo/gtkfishbowl.h
index 837efb7bc7..341d4f8bdd 100644
--- a/demos/gtk-demo/gtkfishbowl.h
+++ b/demos/gtk-demo/gtkfishbowl.h
@@ -55,7 +55,7 @@ void       gtk_fishbowl_set_animating     (GtkFishbowl       *fishbowl,
                                            gboolean           animating);
 gboolean   gtk_fishbowl_get_benchmark     (GtkFishbowl       *fishbowl);
 void       gtk_fishbowl_set_benchmark     (GtkFishbowl       *fishbowl,
-                                           gboolean           animating);
+                                           gboolean           benchmark);
 double     gtk_fishbowl_get_framerate     (GtkFishbowl       *fishbowl);
 gint64     gtk_fishbowl_get_update_delay  (GtkFishbowl       *fishbowl);
 void       gtk_fishbowl_set_update_delay  (GtkFishbowl       *fishbowl,
diff --git a/demos/gtk-demo/hsla.h b/demos/gtk-demo/hsla.h
index 52c6bdc146..9ce8003113 100644
--- a/demos/gtk-demo/hsla.h
+++ b/demos/gtk-demo/hsla.h
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <gdk/gdk.h>
+
 typedef struct _GdkHSLA GdkHSLA;
 
 struct _GdkHSLA {
diff --git a/demos/gtk-demo/nodewidget.h b/demos/gtk-demo/nodewidget.h
index 48036265e2..c70513e606 100644
--- a/demos/gtk-demo/nodewidget.h
+++ b/demos/gtk-demo/nodewidget.h
@@ -5,4 +5,4 @@
 #define NODE_TYPE_WIDGET (node_widget_get_type ())
 G_DECLARE_FINAL_TYPE (NodeWidget, node_widget, NODE, WIDGET, GtkWidget)
 
-GtkWidget * node_widget_new       (const char *file);
+GtkWidget * node_widget_new       (const char *resource);
diff --git a/demos/gtk-demo/suggestionentry.h b/demos/gtk-demo/suggestionentry.h
index ede791c961..9dce18fc9c 100644
--- a/demos/gtk-demo/suggestionentry.h
+++ b/demos/gtk-demo/suggestionentry.h
@@ -43,7 +43,7 @@ GtkListItemFactory *
                 suggestion_entry_get_factory        (SuggestionEntry     *self);
 
 void            suggestion_entry_set_use_filter     (SuggestionEntry     *self,
-                                                     gboolean             use_ilter);
+                                                     gboolean             use_filter);
 gboolean        suggestion_entry_get_use_filter     (SuggestionEntry     *self);
 
 void            suggestion_entry_set_expression     (SuggestionEntry     *self,
diff --git a/gdk/broadway/broadway-server.h b/gdk/broadway/broadway-server.h
index e72023e276..e4f6b4586e 100644
--- a/gdk/broadway/broadway-server.h
+++ b/gdk/broadway/broadway-server.h
@@ -111,7 +111,7 @@ gboolean            broadway_server_surface_translate         (BroadwayServer  *
                                                                int              dx,
                                                                int              dy);
 guint32             broadway_server_upload_texture            (BroadwayServer  *server,
-                                                               GBytes          *texture);
+                                                               GBytes          *bytes);
 void                broadway_server_release_texture           (BroadwayServer  *server,
                                                                guint32          id);
 cairo_surface_t   * broadway_server_create_surface            (int              width,
diff --git a/gdk/broadway/gdkprivate-broadway.h b/gdk/broadway/gdkprivate-broadway.h
index 0295aa1021..a38d1622d3 100644
--- a/gdk/broadway/gdkprivate-broadway.h
+++ b/gdk/broadway/gdkprivate-broadway.h
@@ -56,7 +56,7 @@ void     _gdk_broadway_surface_translate          (GdkSurface *surface,
                                                    int        dx,
                                                    int        dy);
 gboolean _gdk_broadway_moveresize_handle_event    (GdkDisplay *display,
-                                                   BroadwayInputMsg *msg);
+                                                   BroadwayInputMsg *event);
 gboolean _gdk_broadway_moveresize_configure_done  (GdkDisplay *display,
                                                    GdkSurface  *surface);
 void     _gdk_broadway_roundtrip_notify           (GdkSurface  *surface,
diff --git a/gdk/filetransferportalprivate.h b/gdk/filetransferportalprivate.h
index 1a4bb50952..30991af2bf 100644
--- a/gdk/filetransferportalprivate.h
+++ b/gdk/filetransferportalprivate.h
@@ -17,6 +17,7 @@
 
 #pragma once
 
+#include <gio/gio.h>
 
 void     file_transfer_portal_register              (void);
 
diff --git a/gdk/gdkcicpparamsprivate.h b/gdk/gdkcicpparamsprivate.h
index d7ed12c9f4..bd9bbb3817 100644
--- a/gdk/gdkcicpparamsprivate.h
+++ b/gdk/gdkcicpparamsprivate.h
@@ -79,6 +79,6 @@ gdk_cicp_equivalent (const GdkCicp *p1,
   return gdk_cicp_equal (&n1, &n2);
 }
 
-const GdkCicp * gdk_cicp_params_get_cicp (GdkCicpParams *params);
+const GdkCicp * gdk_cicp_params_get_cicp (GdkCicpParams *self);
 
 GdkCicpParams * gdk_cicp_params_new_for_cicp (const GdkCicp  *cicp);
diff --git a/gdk/gdkcolordefs.h b/gdk/gdkcolordefs.h
index 25394cac55..2736353502 100644
--- a/gdk/gdkcolordefs.h
+++ b/gdk/gdkcolordefs.h
@@ -20,6 +20,9 @@
  * and tests, and must not include other headers.
  */
 
+#include <glib.h>
+#include <math.h>
+
 static inline int
 sign (float v)
 {
diff --git a/gdk/gdkcolorimpl.h b/gdk/gdkcolorimpl.h
index 8103b34f89..c6ff198cc7 100644
--- a/gdk/gdkcolorimpl.h
+++ b/gdk/gdkcolorimpl.h
@@ -18,6 +18,8 @@
 
 #pragma once
 
+#include "gdkcolorprivate.h"
+
 #include "gdkcolorstateprivate.h"
 
 
diff --git a/gdk/gdkcolorprivate.h b/gdk/gdkcolorprivate.h
index f12f298ecb..3c72f1a127 100644
--- a/gdk/gdkcolorprivate.h
+++ b/gdk/gdkcolorprivate.h
@@ -79,8 +79,8 @@ void              gdk_color_init_from_rgba      (GdkColor               *self,
                                                  const GdkRGBA          *rgba);
 void              gdk_color_finish              (GdkColor               *self);
 
-gboolean          gdk_color_equal               (const GdkColor         *color1,
-                                                 const GdkColor         *color2);
+gboolean          gdk_color_equal               (const GdkColor         *self,
+                                                 const GdkColor         *other);
 gboolean          gdk_color_is_clear            (const GdkColor         *self);
 gboolean          gdk_color_is_opaque           (const GdkColor         *self);
 
diff --git a/gdk/gdkcolorstateprivate.h b/gdk/gdkcolorstateprivate.h
index be98807f0c..cea7bc82fd 100644
--- a/gdk/gdkcolorstateprivate.h
+++ b/gdk/gdkcolorstateprivate.h
@@ -78,7 +78,7 @@ extern GdkDefaultColorState gdk_default_color_states[GDK_COLOR_STATE_N_IDS];
                                        (GdkDefaultColorState *) (c) < &gdk_default_color_states[GDK_COLOR_STATE_N_IDS])
 #define GDK_DEFAULT_COLOR_STATE_ID(c) ((GdkColorStateId) (((GdkDefaultColorState *) c) - gdk_default_color_states))
 
-const char *    gdk_color_state_get_name                (GdkColorState          *color_state);
+const char *    gdk_color_state_get_name                (GdkColorState          *self);
 GdkColorState * gdk_color_state_get_no_srgb_tf          (GdkColorState          *self);
 
 GdkColorState * gdk_color_state_new_for_cicp            (const GdkCicp          *cicp,
diff --git a/gdk/gdkdeviceprivate.h b/gdk/gdkdeviceprivate.h
index fb7eadc876..b24d8ad9d1 100644
--- a/gdk/gdkdeviceprivate.h
+++ b/gdk/gdkdeviceprivate.h
@@ -117,7 +117,7 @@ struct _GdkDeviceClass
 };
 
 void  _gdk_device_set_associated_device (GdkDevice *device,
-                                         GdkDevice *relative);
+                                         GdkDevice *associated);
 
 void  _gdk_device_reset_axes (GdkDevice   *device);
 guint _gdk_device_add_axis   (GdkDevice   *device,
diff --git a/gdk/gdkdisplayprivate.h b/gdk/gdkdisplayprivate.h
index 9420b1e182..7985e4069c 100644
--- a/gdk/gdkdisplayprivate.h
+++ b/gdk/gdkdisplayprivate.h
@@ -240,15 +240,15 @@ GdkVulkanContext *  gdk_display_create_vulkan_context (GdkDisplay       *self,
                                                        GdkSurface       *surface,
                                                        GError          **error);
 
-GdkGLContext *      gdk_display_get_gl_context        (GdkDisplay       *display);
+GdkGLContext *      gdk_display_get_gl_context        (GdkDisplay       *self);
 
-gboolean            gdk_display_init_egl              (GdkDisplay       *display,
+gboolean            gdk_display_init_egl              (GdkDisplay       *self,
                                                        int /*EGLenum*/   platform,
                                                        gpointer          native_display,
                                                        gboolean          allow_any,
                                                        GError          **error);
-gpointer            gdk_display_get_egl_display       (GdkDisplay       *display);
-gpointer            gdk_display_get_egl_config        (GdkDisplay       *display,
+gpointer            gdk_display_get_egl_display       (GdkDisplay       *self);
+gpointer            gdk_display_get_egl_config        (GdkDisplay       *self,
                                                        GdkMemoryDepth    depth);
 
 void                gdk_display_set_rgba              (GdkDisplay       *display,
@@ -289,7 +289,7 @@ void gdk_display_set_double_click_time     (GdkDisplay   *display,
 void gdk_display_set_double_click_distance (GdkDisplay   *display,
                                             guint         distance);
 void gdk_display_set_cursor_theme          (GdkDisplay   *display,
-                                            const char   *theme,
+                                            const char   *name,
                                             int           size);
 
 G_END_DECLS
diff --git a/gdk/gdkdmabufdownloaderprivate.h b/gdk/gdkdmabufdownloaderprivate.h
index 6053bfbfa7..4d4d11c374 100644
--- a/gdk/gdkdmabufdownloaderprivate.h
+++ b/gdk/gdkdmabufdownloaderprivate.h
@@ -25,11 +25,11 @@ struct _GdkDmabufDownloaderInterface
                                                                  gsize                           stride);
 };
 
-void                    gdk_dmabuf_downloader_close             (GdkDmabufDownloader            *downloader);
-gboolean                gdk_dmabuf_downloader_supports          (GdkDmabufDownloader            *downloader,
+void                    gdk_dmabuf_downloader_close             (GdkDmabufDownloader            *self);
+gboolean                gdk_dmabuf_downloader_supports          (GdkDmabufDownloader            *self,
                                                                  GdkDmabufTexture               *texture,
                                                                  GError                        **error);
-void                    gdk_dmabuf_downloader_download          (GdkDmabufDownloader            *downloader,
+void                    gdk_dmabuf_downloader_download          (GdkDmabufDownloader            *self,
                                                                  GdkDmabufTexture               *texture,
                                                                  GdkMemoryFormat                 format,
                                                                  GdkColorState                  *color_state,
diff --git a/gdk/gdkdmabuftexturebuilderprivate.h b/gdk/gdkdmabuftexturebuilderprivate.h
index fe725051fc..d95438c684 100644
--- a/gdk/gdkdmabuftexturebuilderprivate.h
+++ b/gdk/gdkdmabuftexturebuilderprivate.h
@@ -5,9 +5,9 @@
 
 G_BEGIN_DECLS
 
-const GdkDmabuf *       gdk_dmabuf_texture_builder_get_dmabuf   (GdkDmabufTextureBuilder *builder);
+const GdkDmabuf *       gdk_dmabuf_texture_builder_get_dmabuf   (GdkDmabufTextureBuilder *self);
 
-void                    gdk_dmabuf_texture_builder_set_dmabuf   (GdkDmabufTextureBuilder *builder,
+void                    gdk_dmabuf_texture_builder_set_dmabuf   (GdkDmabufTextureBuilder *self,
                                                                  const GdkDmabuf         *dmabuf);
 
 G_END_DECLS
diff --git a/gdk/gdkdrawcontext.c b/gdk/gdkdrawcontext.c
index f73092e384..7935111f1d 100644
--- a/gdk/gdkdrawcontext.c
+++ b/gdk/gdkdrawcontext.c
@@ -511,9 +511,9 @@ gdk_draw_context_end_frame (GdkDrawContext *context)
  *   Use `GskRenderNode` and `GskRenderer`.
  */
 const cairo_region_t *
-_gdk_draw_context_get_frame_region (GdkDrawContext *context)
+_gdk_draw_context_get_frame_region (GdkDrawContext *self)
 {
-  GdkDrawContextPrivate *priv = gdk_draw_context_get_instance_private (context);
+  GdkDrawContextPrivate *priv = gdk_draw_context_get_instance_private (self);
 
   return priv->frame_region;
 }
diff --git a/gdk/gdkglcontextprivate.h b/gdk/gdkglcontextprivate.h
index 3d3a22343c..092cd158d0 100644
--- a/gdk/gdkglcontextprivate.h
+++ b/gdk/gdkglcontextprivate.h
@@ -133,16 +133,16 @@ void                    gdk_gl_context_set_version              (GdkGLContext
                                                                  const GdkGLVersion     *version);
 void                    gdk_gl_context_set_is_legacy            (GdkGLContext           *context,
                                                                  gboolean                is_legacy);
-gboolean                gdk_gl_context_check_gl_version         (GdkGLContext           *context,
+gboolean                gdk_gl_context_check_gl_version         (GdkGLContext           *self,
                                                                  const GdkGLVersion     *gl_version,
                                                                  const GdkGLVersion     *gles_version);
 
 static inline gboolean
-gdk_gl_context_check_version (GdkGLContext *context,
+gdk_gl_context_check_version (GdkGLContext *self,
                               const char   *gl_version,
                               const char   *gles_version)
 {
-  return gdk_gl_context_check_gl_version (context,
+  return gdk_gl_context_check_gl_version (self,
                                           gl_version ? &GDK_GL_VERSION_STRING (gl_version) : NULL,
                                           gles_version ? &GDK_GL_VERSION_STRING (gles_version) : NULL);
 }
diff --git a/gdk/gdkmemoryformat.c b/gdk/gdkmemoryformat.c
index ff9072345d..0e56adf9dd 100644
--- a/gdk/gdkmemoryformat.c
+++ b/gdk/gdkmemoryformat.c
@@ -2479,8 +2479,8 @@ void
 gdk_memory_convert_color_state (guchar          *data,
                                 gsize            stride,
                                 GdkMemoryFormat  format,
-                                GdkColorState   *src_cs,
-                                GdkColorState   *dest_cs,
+                                GdkColorState   *src_color_state,
+                                GdkColorState   *dest_color_state,
                                 gsize            width,
                                 gsize            height)
 {
@@ -2488,24 +2488,24 @@ gdk_memory_convert_color_state (guchar          *data,
     .data = data,
     .stride = stride,
     .format = format,
-    .src_cs = src_cs,
-    .dest_cs = dest_cs,
+    .src_cs = src_color_state,
+    .dest_cs = dest_color_state,
     .width = width,
     .height = height,
   };
 
-  if (gdk_color_state_equal (src_cs, dest_cs))
+  if (gdk_color_state_equal (src_color_state, dest_color_state))
     return;
 
   if (format == GDK_MEMORY_B8G8R8A8_PREMULTIPLIED &&
-      src_cs == GDK_COLOR_STATE_SRGB &&
-      dest_cs == GDK_COLOR_STATE_SRGB_LINEAR)
+      src_color_state == GDK_COLOR_STATE_SRGB &&
+      dest_color_state == GDK_COLOR_STATE_SRGB_LINEAR)
     {
       gdk_parallel_task_run (gdk_memory_convert_color_state_srgb_to_srgb_linear, &mc);
     }
   else if (format == GDK_MEMORY_B8G8R8A8_PREMULTIPLIED &&
-           src_cs == GDK_COLOR_STATE_SRGB_LINEAR &&
-           dest_cs == GDK_COLOR_STATE_SRGB)
+           src_color_state == GDK_COLOR_STATE_SRGB_LINEAR &&
+           dest_color_state == GDK_COLOR_STATE_SRGB)
     {
       gdk_parallel_task_run (gdk_memory_convert_color_state_srgb_linear_to_srgb, &mc);
     }
diff --git a/gdk/gdkmemoryformatprivate.h b/gdk/gdkmemoryformatprivate.h
index 323ac927ab..994e8e845c 100644
--- a/gdk/gdkmemoryformatprivate.h
+++ b/gdk/gdkmemoryformatprivate.h
@@ -96,11 +96,11 @@ const char *            gdk_memory_format_get_name          (GdkMemoryFormat
 void                    gdk_memory_convert                  (guchar                     *dest_data,
                                                              gsize                       dest_stride,
                                                              GdkMemoryFormat             dest_format,
-                                                             GdkColorState              *src_cs,
+                                                             GdkColorState              *dest_cs,
                                                              const guchar               *src_data,
                                                              gsize                       src_stride,
                                                              GdkMemoryFormat             src_format,
-                                                             GdkColorState              *dest_cs,
+                                                             GdkColorState              *src_cs,
                                                              gsize                       width,
                                                              gsize                       height);
 void                    gdk_memory_convert_color_state      (guchar                     *data,
diff --git a/gdk/gen-keyname-table.pl b/gdk/gen-keyname-table.pl
index a193a7a042..9c14c13928 100755
--- a/gdk/gen-keyname-table.pl
+++ b/gdk/gen-keyname-table.pl
@@ -63,8 +63,8 @@ print ";\n\n";
 
 print <<EOT;
 typedef struct {
-    guint  keyval;
-    guint  offset;
+    unsigned int  keyval;
+    unsigned int  offset;
 } gdk_key;
 
 static const gdk_key gdk_keys_by_keyval[] = {
diff --git a/gsk/gpu/gskgpubuffer.c b/gsk/gpu/gskgpubuffer.c
index e8521defb0..961bfb2a5c 100644
--- a/gsk/gpu/gskgpubuffer.c
+++ b/gsk/gpu/gskgpubuffer.c
@@ -52,11 +52,11 @@ gsk_gpu_buffer_map (GskGpuBuffer *self)
 
 void
 gsk_gpu_buffer_unmap (GskGpuBuffer *self,
-                      gsize         size)
+                      gsize         used)
 {
-  GSK_GPU_BUFFER_GET_CLASS (self)->unmap (self, size);
+  GSK_GPU_BUFFER_GET_CLASS (self)->unmap (self, used);
 
-  profiler_buffer_uploads += size;
+  profiler_buffer_uploads += used;
   gdk_profiler_set_int_counter (profiler_buffer_uploads_id, profiler_buffer_uploads);
 }
 
diff --git a/gsk/gpu/gskvulkanmemoryprivate.h b/gsk/gpu/gskvulkanmemoryprivate.h
index 5fa7f615de..fdc6bbea07 100644
--- a/gsk/gpu/gskvulkanmemoryprivate.h
+++ b/gsk/gpu/gskvulkanmemoryprivate.h
@@ -44,8 +44,8 @@ static inline void      gsk_vulkan_free                                 (GskVulk
                                                                          GskVulkanAllocation            *alloc);
 
 static inline GskVulkanAllocator *
-                        gsk_vulkan_allocator_ref                        (GskVulkanAllocator             *allocator);
-static inline void      gsk_vulkan_allocator_unref                      (GskVulkanAllocator             *allocator);
+                        gsk_vulkan_allocator_ref                        (GskVulkanAllocator             *self);
+static inline void      gsk_vulkan_allocator_unref                      (GskVulkanAllocator             *self);
 
 GskVulkanAllocator *    gsk_vulkan_direct_allocator_new                 (VkDevice                        device,
                                                                          uint32_t                        vk_type_index,
diff --git a/gtk/gtkpango.c b/gtk/gtkpango.c
index 901af1b603..954cf28aac 100644
--- a/gtk/gtkpango.c
+++ b/gtk/gtkpango.c
@@ -450,9 +450,9 @@ pango_stretch_to_string (PangoStretch stretch)
 }
 
 const char *
-pango_underline_to_string (PangoUnderline value)
+pango_underline_to_string (PangoUnderline underline)
 {
-  switch (value)
+  switch (underline)
     {
     case PANGO_UNDERLINE_NONE:
       return "none";
@@ -473,9 +473,9 @@ pango_underline_to_string (PangoUnderline value)
 }
 
 const char *
-pango_overline_to_string (PangoOverline value)
+pango_overline_to_string (PangoOverline overline)
 {
-  switch (value)
+  switch (overline)
     {
     case PANGO_OVERLINE_NONE:
       return "none";
diff --git a/gtk/gtkpangoprivate.h b/gtk/gtkpangoprivate.h
index e5eaefd97c..6efc2724ed 100644
--- a/gtk/gtkpangoprivate.h
+++ b/gtk/gtkpangoprivate.h
@@ -57,7 +57,7 @@ gtk_pango_attribute_start_element (GtkBuildableParseContext  *context,
 
 const char *pango_wrap_mode_to_string (PangoWrapMode mode);
 const char *pango_underline_to_string (PangoUnderline underline);
-const char *pango_overline_to_string (PangoOverline underline);
+const char *pango_overline_to_string (PangoOverline overline);
 const char *pango_stretch_to_string (PangoStretch stretch);
 const char *pango_style_to_string (PangoStyle style);
 const char *pango_variant_to_string (PangoVariant variant);
diff --git a/gtk/gtktextutilprivate.h b/gtk/gtktextutilprivate.h
index 37e1ed29ff..af16087691 100644
--- a/gtk/gtktextutilprivate.h
+++ b/gtk/gtktextutilprivate.h
@@ -24,10 +24,10 @@
 
 #pragma once
 
-G_BEGIN_DECLS
-
 #include "gtktextbuffer.h"
 
+G_BEGIN_DECLS
+
 /* This is a private uninstalled header shared between
  * GtkTextView and GtkEntry
  */
diff --git a/testsuite/gsk/path-utils.h b/testsuite/gsk/path-utils.h
index ce475e9acd..e1d63d010d 100644
--- a/testsuite/gsk/path-utils.h
+++ b/testsuite/gsk/path-utils.h
@@ -19,6 +19,8 @@
 
 #pragma once
 
+#include <gsk/gsk.h>
+
 void assert_path_equal_func (const char *domain,
                              const char *file,
                              int         line,
diff --git a/testsuite/reftests/gtk-reftest.h b/testsuite/reftests/gtk-reftest.h
index 624d70db13..820e340507 100644
--- a/testsuite/reftests/gtk-reftest.h
+++ b/testsuite/reftests/gtk-reftest.h
@@ -17,6 +17,8 @@
 
 #pragma once
 
+#include <glib.h>
+
 G_BEGIN_DECLS
 
 /* reftest-snapshot.c */
diff --git a/testsuite/testutils.h b/testsuite/testutils.h
index 107d5e806c..bbb720d6ff 100644
--- a/testsuite/testutils.h
+++ b/testsuite/testutils.h
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <glib.h>
+
 char * diff_with_file (const char  *file1,
                        const char  *text,
                        gssize       len,
diff --git a/tools/gtk-image-tool.h b/tools/gtk-image-tool.h
index 7ad1a61901..e5499022d6 100644
--- a/tools/gtk-image-tool.h
+++ b/tools/gtk-image-tool.h
@@ -1,6 +1,7 @@
-
 #pragma once
 
+#include <gdk/gdk.h>
+
 void do_compare     (int *argc, const char ***argv);
 void do_convert     (int *argc, const char ***argv);
 void do_info        (int *argc, const char ***argv);
diff --git a/tools/gtk-path-tool.h b/tools/gtk-path-tool.h
index aa4236b86c..891b647a65 100644
--- a/tools/gtk-path-tool.h
+++ b/tools/gtk-path-tool.h
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <gsk/gsk.h>
+
 void do_info      (int *argc, const char ***argv);
 void do_decompose (int *argc, const char ***argv);
 void do_restrict  (int *argc, const char ***argv);
diff --git a/tools/gtk-rendernode-tool.h b/tools/gtk-rendernode-tool.h
index 015082c883..6b9db9f213 100644
--- a/tools/gtk-rendernode-tool.h
+++ b/tools/gtk-rendernode-tool.h
@@ -1,6 +1,7 @@
-
 #pragma once
 
+#include <gsk/gsk.h>
+
 void do_benchmark   (int *argc, const char ***argv);
 void do_compare     (int *argc, const char ***argv);
 void do_info        (int *argc, const char ***argv);