diff --git a/gst-libs/gst/gl/egl/gstglcontext_egl.h b/gst-libs/gst/gl/egl/gstglcontext_egl.h
index 1923664d0f..40adc99788 100644
--- a/gst-libs/gst/gl/egl/gstglcontext_egl.h
+++ b/gst-libs/gst/gl/egl/gstglcontext_egl.h
@@ -32,7 +32,7 @@ G_BEGIN_DECLS
 typedef struct _GstGLContextEGL GstGLContextEGL;
 typedef struct _GstGLContextEGLClass GstGLContextEGLClass;
 
-GType gst_gl_context_egl_get_type     (void);
+G_GNUC_INTERNAL GType gst_gl_context_egl_get_type (void);
 #define GST_TYPE_GL_CONTEXT_EGL         (gst_gl_context_egl_get_type())
 
 /* FIXME: remove this when moving to -base */
@@ -84,8 +84,13 @@ struct _GstGLContextEGLClass
   GstGLContextClass parent;
 };
 
+G_GNUC_INTERNAL
 GstGLContextEGL *   gst_gl_context_egl_new                  (GstGLDisplay * display);
+
+G_GNUC_INTERNAL
 guintptr            gst_gl_context_egl_get_current_context  (void);
+
+G_GNUC_INTERNAL
 gpointer            gst_gl_context_egl_get_proc_address     (GstGLAPI gl_api, const gchar * name);
 
 G_END_DECLS
diff --git a/gst-libs/gst/gl/gstglcontext.c b/gst-libs/gst/gl/gstglcontext.c
index aed46185ef..8c1b7b5972 100644
--- a/gst-libs/gst/gl/gstglcontext.c
+++ b/gst-libs/gst/gl/gstglcontext.c
@@ -234,7 +234,7 @@ typedef struct
 } GstGLWrappedContextClass;
 
 #define GST_TYPE_GL_WRAPPED_CONTEXT (gst_gl_wrapped_context_get_type())
-GType gst_gl_wrapped_context_get_type (void);
+static GType gst_gl_wrapped_context_get_type (void);
 G_DEFINE_TYPE (GstGLWrappedContext, gst_gl_wrapped_context,
     GST_TYPE_GL_CONTEXT);
 
diff --git a/gst-libs/gst/gl/gstglwindow.c b/gst-libs/gst/gl/gstglwindow.c
index c2e8be07c0..4a5891a53e 100644
--- a/gst-libs/gst/gl/gstglwindow.c
+++ b/gst-libs/gst/gl/gstglwindow.c
@@ -115,7 +115,7 @@ typedef struct _GstGLDummyWindowCass
   GstGLWindowClass parent;
 } GstGLDummyWindowClass;
 
-GstGLDummyWindow *gst_gl_dummy_window_new (void);
+static GstGLDummyWindow *gst_gl_dummy_window_new (void);
 
 enum
 {
@@ -964,7 +964,7 @@ gst_gl_window_resize (GstGLWindow * window, guint width, guint height)
   window->queue_resize = FALSE;
 }
 
-GType gst_gl_dummy_window_get_type (void);
+static GType gst_gl_dummy_window_get_type (void);
 
 G_DEFINE_TYPE (GstGLDummyWindow, gst_gl_dummy_window, GST_TYPE_GL_WINDOW);
 
@@ -1009,7 +1009,7 @@ gst_gl_dummy_window_init (GstGLDummyWindow * dummy)
   dummy->handle = 0;
 }
 
-GstGLDummyWindow *
+static GstGLDummyWindow *
 gst_gl_dummy_window_new (void)
 {
   GstGLDummyWindow *window;
diff --git a/gst-libs/gst/gl/wayland/gstglwindow_wayland_egl.h b/gst-libs/gst/gl/wayland/gstglwindow_wayland_egl.h
index 16a0543ea3..07c7ad1b95 100644
--- a/gst-libs/gst/gl/wayland/gstglwindow_wayland_egl.h
+++ b/gst-libs/gst/gl/wayland/gstglwindow_wayland_egl.h
@@ -95,10 +95,13 @@ struct _GstGLWindowWaylandEGLClass {
   gpointer _reserved[GST_PADDING];
 };
 
-GType gst_gl_window_wayland_egl_get_type     (void);
+G_GNUC_INTERNAL
+GType                   gst_gl_window_wayland_egl_get_type (void);
 
+G_GNUC_INTERNAL
 GstGLWindowWaylandEGL * gst_gl_window_wayland_egl_new  (GstGLDisplay * display);
 
+G_GNUC_INTERNAL
 void gst_gl_window_wayland_egl_create_window (GstGLWindowWaylandEGL * window_egl);
 
 G_END_DECLS
diff --git a/gst-libs/gst/gl/x11/gstglcontext_glx.c b/gst-libs/gst/gl/x11/gstglcontext_glx.c
index 795cd9b981..06b7b6c5c5 100644
--- a/gst-libs/gst/gl/x11/gstglcontext_glx.c
+++ b/gst-libs/gst/gl/x11/gstglcontext_glx.c
@@ -55,7 +55,7 @@ static gboolean gst_gl_context_glx_create_context (GstGLContext *
 static void gst_gl_context_glx_destroy_context (GstGLContext * context);
 static gboolean gst_gl_context_glx_choose_format (GstGLContext *
     context, GError ** error);
-GstGLAPI gst_gl_context_glx_get_gl_api (GstGLContext * context);
+static GstGLAPI gst_gl_context_glx_get_gl_api (GstGLContext * context);
 static GstGLPlatform gst_gl_context_glx_get_gl_platform (GstGLContext *
     context);
 static void gst_gl_context_glx_get_gl_platform_version (GstGLContext * context,
diff --git a/gst-libs/gst/gl/x11/gstglcontext_glx.h b/gst-libs/gst/gl/x11/gstglcontext_glx.h
index a58c70df45..e3eb8fe3c7 100644
--- a/gst-libs/gst/gl/x11/gstglcontext_glx.h
+++ b/gst-libs/gst/gl/x11/gstglcontext_glx.h
@@ -28,7 +28,7 @@
 G_BEGIN_DECLS
 
 #define GST_TYPE_GL_CONTEXT_GLX         (gst_gl_context_glx_get_type())
-GType gst_gl_context_glx_get_type     (void);
+G_GNUC_INTERNAL GType gst_gl_context_glx_get_type (void);
 
 /* FIXME: remove this when moving to -base */
 #ifndef GST_DISABLE_DEPRECATED
@@ -63,8 +63,13 @@ struct _GstGLContextGLXClass {
   gpointer _reserved[GST_PADDING];
 };
 
+G_GNUC_INTERNAL
 GstGLContextGLX *   gst_gl_context_glx_new                  (GstGLDisplay * display);
+
+G_GNUC_INTERNAL
 guintptr            gst_gl_context_glx_get_current_context  (void);
+
+G_GNUC_INTERNAL
 gpointer            gst_gl_context_glx_get_proc_address     (GstGLAPI gl_api, const gchar * name);
 
 G_END_DECLS
diff --git a/gst-libs/gst/gl/x11/gstgldisplay_x11.c b/gst-libs/gst/gl/x11/gstgldisplay_x11.c
index c19d7a61a2..07c2962145 100644
--- a/gst-libs/gst/gl/x11/gstgldisplay_x11.c
+++ b/gst-libs/gst/gl/x11/gstgldisplay_x11.c
@@ -34,7 +34,9 @@ G_DEFINE_TYPE (GstGLDisplayX11, gst_gl_display_x11, GST_TYPE_GL_DISPLAY);
 static void gst_gl_display_x11_finalize (GObject * object);
 static guintptr gst_gl_display_x11_get_handle (GstGLDisplay * display);
 
-gboolean gst_gl_display_x11_handle_event (GstGLDisplayX11 * display_x11);
+G_GNUC_INTERNAL
+    gboolean gst_gl_display_x11_handle_event (GstGLDisplayX11 * display_x11);
+
 extern gboolean gst_gl_window_x11_handle_event (GstGLWindowX11 * window_x11,
     xcb_generic_event_t * event);
 
diff --git a/gst-libs/gst/gl/x11/gstglwindow_x11.c b/gst-libs/gst/gl/x11/gstglwindow_x11.c
index 62e901868b..a98b2c3994 100644
--- a/gst-libs/gst/gl/x11/gstglwindow_x11.c
+++ b/gst-libs/gst/gl/x11/gstglwindow_x11.c
@@ -41,7 +41,8 @@
 #define gst_gl_window_x11_parent_class parent_class
 G_DEFINE_TYPE (GstGLWindowX11, gst_gl_window_x11, GST_TYPE_GL_WINDOW);
 
-gboolean gst_gl_window_x11_handle_event (GstGLWindowX11 * window_x11,
+G_GNUC_INTERNAL
+    gboolean gst_gl_window_x11_handle_event (GstGLWindowX11 * window_x11,
     xcb_generic_event_t * event);
 
 /* X error trap */
@@ -67,23 +68,23 @@ struct _GstGLWindowX11Private
   GstVideoRectangle render_rect;
 };
 
-guintptr gst_gl_window_x11_get_display (GstGLWindow * window);
+static guintptr gst_gl_window_x11_get_display (GstGLWindow * window);
 guintptr gst_gl_window_x11_get_gl_context (GstGLWindow * window);
 gboolean gst_gl_window_x11_activate (GstGLWindow * window, gboolean activate);
-void gst_gl_window_x11_set_window_handle (GstGLWindow * window,
+static void gst_gl_window_x11_set_window_handle (GstGLWindow * window,
     guintptr handle);
 static gboolean gst_gl_window_x11_set_render_rectangle (GstGLWindow * window,
     int x, int y, int width, int height);
-guintptr gst_gl_window_x11_get_window_handle (GstGLWindow * window);
+static guintptr gst_gl_window_x11_get_window_handle (GstGLWindow * window);
 static void gst_gl_window_x11_set_preferred_size (GstGLWindow * window,
     gint width, gint height);
-void gst_gl_window_x11_show (GstGLWindow * window);
-void gst_gl_window_x11_draw (GstGLWindow * window);
+static void gst_gl_window_x11_show (GstGLWindow * window);
+static void gst_gl_window_x11_draw (GstGLWindow * window);
 gboolean gst_gl_window_x11_create_context (GstGLWindow * window,
     GstGLAPI gl_api, guintptr external_gl_context, GError ** error);
-gboolean gst_gl_window_x11_open (GstGLWindow * window, GError ** error);
-void gst_gl_window_x11_close (GstGLWindow * window);
-void gst_gl_window_x11_handle_events (GstGLWindow * window,
+static gboolean gst_gl_window_x11_open (GstGLWindow * window, GError ** error);
+static void gst_gl_window_x11_close (GstGLWindow * window);
+static void gst_gl_window_x11_handle_events (GstGLWindow * window,
     gboolean handle_events);
 
 static void
@@ -144,7 +145,7 @@ gst_gl_window_x11_new (GstGLDisplay * display)
   return window;
 }
 
-gboolean
+static gboolean
 gst_gl_window_x11_open (GstGLWindow * window, GError ** error)
 {
   GstGLWindowX11 *window_x11 = GST_GL_WINDOW_X11 (window);
@@ -261,7 +262,7 @@ gst_gl_window_x11_create_window (GstGLWindowX11 * window_x11)
   return TRUE;
 }
 
-void
+static void
 gst_gl_window_x11_close (GstGLWindow * window)
 {
   GstGLWindowX11 *window_x11 = GST_GL_WINDOW_X11 (window);
@@ -283,7 +284,7 @@ gst_gl_window_x11_close (GstGLWindow * window)
 }
 
 /* called by the gl thread */
-void
+static void
 gst_gl_window_x11_set_window_handle (GstGLWindow * window, guintptr id)
 {
   GstGLWindowX11 *window_x11;
@@ -378,7 +379,7 @@ gst_gl_window_x11_set_render_rectangle (GstGLWindow * window,
   return TRUE;
 }
 
-guintptr
+static guintptr
 gst_gl_window_x11_get_window_handle (GstGLWindow * window)
 {
   GstGLWindowX11 *window_x11;
@@ -417,7 +418,7 @@ _show_window (GstGLWindow * window)
   }
 }
 
-void
+static void
 gst_gl_window_x11_show (GstGLWindow * window)
 {
   gst_gl_window_send_message (window, (GstGLWindowCB) _show_window, window);
@@ -491,13 +492,13 @@ draw_cb (gpointer data)
 }
 
 /* Not called by the gl thread */
-void
+static void
 gst_gl_window_x11_draw (GstGLWindow * window)
 {
   gst_gl_window_send_message (window, (GstGLWindowCB) draw_cb, window);
 }
 
-void
+static void
 gst_gl_window_x11_handle_events (GstGLWindow * window, gboolean handle_events)
 {
   GstGLWindowX11 *window_x11;
@@ -657,7 +658,7 @@ gst_gl_window_x11_untrap_x_errors (void)
   return TrappedErrorCode;
 }
 
-guintptr
+static guintptr
 gst_gl_window_x11_get_display (GstGLWindow * window)
 {
   GstGLWindowX11 *window_x11 = GST_GL_WINDOW_X11 (window);
diff --git a/gst-libs/gst/gl/x11/gstglwindow_x11.h b/gst-libs/gst/gl/x11/gstglwindow_x11.h
index 77092ba60b..e612ff1907 100644
--- a/gst-libs/gst/gl/x11/gstglwindow_x11.h
+++ b/gst-libs/gst/gl/x11/gstglwindow_x11.h
@@ -29,7 +29,8 @@
 G_BEGIN_DECLS
 
 #define GST_TYPE_GL_WINDOW_X11         (gst_gl_window_x11_get_type())
-GType gst_gl_window_x11_get_type     (void);
+G_GNUC_INTERNAL GType gst_gl_window_x11_get_type (void);
+
 #define GST_GL_WINDOW_X11(o)           (G_TYPE_CHECK_INSTANCE_CAST((o), GST_TYPE_GL_WINDOW_X11, GstGLWindowX11))
 #define GST_GL_WINDOW_X11_CLASS(k)     (G_TYPE_CHECK_CLASS((k), GST_TYPE_GL_WINDOW_X11, GstGLWindowX11Class))
 #define GST_IS_GL_WINDOW_X11(o)        (G_TYPE_CHECK_INSTANCE_TYPE((o), GST_TYPE_GL_WINDOW_X11))
@@ -93,11 +94,16 @@ struct _GstGLWindowX11Class {
   gpointer _reserved[GST_PADDING_LARGE];
 };
 
+G_GNUC_INTERNAL
 GstGLWindowX11 * gst_gl_window_x11_new (GstGLDisplay * display);
 
+G_GNUC_INTERNAL
 void gst_gl_window_x11_trap_x_errors (void);
+
+G_GNUC_INTERNAL
 gint gst_gl_window_x11_untrap_x_errors (void);
 
+G_GNUC_INTERNAL
 gboolean gst_gl_window_x11_create_window (GstGLWindowX11 * window_x11);
 
 G_END_DECLS
diff --git a/gst-libs/gst/gl/x11/xcb_event_source.c b/gst-libs/gst/gl/x11/xcb_event_source.c
index 4077223945..8dbb15398a 100644
--- a/gst-libs/gst/gl/x11/xcb_event_source.c
+++ b/gst-libs/gst/gl/x11/xcb_event_source.c
@@ -29,7 +29,9 @@
 #include "gstgldisplay_x11.h"
 #include "gstglwindow_x11.h"
 
-extern gboolean gst_gl_display_x11_handle_event (GstGLDisplayX11 * display_x11);
+G_GNUC_INTERNAL
+    extern gboolean gst_gl_display_x11_handle_event (GstGLDisplayX11 *
+    display_x11);
 
 typedef struct _XCBEventSource
 {