diff --git a/src/apprt/gtk-ng/class/application.zig b/src/apprt/gtk-ng/class/application.zig
index bbe3bfcb5..fc6f574d5 100644
--- a/src/apprt/gtk-ng/class/application.zig
+++ b/src/apprt/gtk-ng/class/application.zig
@@ -779,7 +779,7 @@ const Action = struct {
 /// given the runtime environment or configuration.
 ///
 /// This must be called BEFORE GTK initialization.
-fn setGtkEnv(config: *const Config) error{NoSpaceLeft}!void {
+fn setGtkEnv(config: *const CoreConfig) error{NoSpaceLeft}!void {
     assert(gtk.isInitialized() == 0);
 
     var gdk_debug: struct {