diff --git a/tests/gpgscm/scheme.c b/tests/gpgscm/scheme.c
index e011deaba..673d19928 100644
--- a/tests/gpgscm/scheme.c
+++ b/tests/gpgscm/scheme.c
@@ -5045,7 +5045,7 @@ int scheme_init_custom_alloc(scheme *sc, func_alloc malloc, func_dealloc free) {
   car(sc->EOF_OBJ) = cdr(sc->EOF_OBJ) = sc->EOF_OBJ;
   /* init sink */
   typeflag(sc->sink) = (T_SINK | T_PAIR | MARK);
-  car(sc->sink) = sc->NIL;
+  car(sc->sink) = cdr(sc->sink) = sc->NIL;
   /* init c_nest */
   sc->c_nest = sc->NIL;