diff --git a/src/c/alloc_2.d b/src/c/alloc_2.d
index bbf407689..13ceec232 100755
--- a/src/c/alloc_2.d
+++ b/src/c/alloc_2.d
@@ -1234,15 +1234,15 @@ ecl_mark_env(struct cl_env_struct *env)
 {
 #if 1
 	if (env->stack) {
-		GC_push_conditional((void *)env->stack, (void *)env->stack_top, 0);
+		GC_push_conditional((void *)env->stack, (void *)env->stack_top, 1);
 		GC_set_mark_bit((void *)env->stack);
 	}
 	if (env->frs_top) {
-		GC_push_conditional((void *)env->frs_org, (void *)(env->frs_top+1), 0);
+		GC_push_conditional((void *)env->frs_org, (void *)(env->frs_top+1), 1);
 		GC_set_mark_bit((void *)env->frs_org);
 	}
 	if (env->bds_top) {
-		GC_push_conditional((void *)env->bds_org, (void *)(env->bds_top+1), 0);
+		GC_push_conditional((void *)env->bds_org, (void *)(env->bds_top+1), 1);
 		GC_set_mark_bit((void *)env->bds_org);
 	}
 #endif