diff --git a/gst-libs/gst/vulkan/cocoa/gstvkcocoa_utils.h b/gst-libs/gst/vulkan/cocoa/gstvkcocoa_utils.h
index a111fe28a4..8958854699 100644
--- a/gst-libs/gst/vulkan/cocoa/gstvkcocoa_utils.h
+++ b/gst-libs/gst/vulkan/cocoa/gstvkcocoa_utils.h
@@ -48,6 +48,7 @@ G_BEGIN_DECLS
 
 typedef void (*GstVulkanWindowFunc) (gpointer data);
 
+G_GNUC_INTERNAL
 void _invoke_on_main (GstVulkanWindowFunc func, gpointer data, GDestroyNotify notify);
 
 G_END_DECLS
diff --git a/gst-libs/gst/vulkan/ios/gstvkios_utils.h b/gst-libs/gst/vulkan/ios/gstvkios_utils.h
index 646b81c33d..200d7cf6a6 100644
--- a/gst-libs/gst/vulkan/ios/gstvkios_utils.h
+++ b/gst-libs/gst/vulkan/ios/gstvkios_utils.h
@@ -34,6 +34,7 @@ G_BEGIN_DECLS
 
 typedef void (*GstVulkanWindowFunc) (gpointer data);
 
+G_GNUC_INTERNAL
 void _invoke_on_main (GstVulkanWindowFunc func, gpointer data, GDestroyNotify notify);
 
 G_END_DECLS