diff --git a/racket/src/racket/src/eval.c b/racket/src/racket/src/eval.c
index 49ec11910b..e7aa77c07a 100644
--- a/racket/src/racket/src/eval.c
+++ b/racket/src/racket/src/eval.c
@@ -6150,6 +6150,7 @@ static void mark_pruned_prefixes(struct NewGC *gc) XFORM_SKIP_PROC
           cl->vals[closure_size-1] = (Scheme_Object *)pf;
         } else {
           MZ_ASSERT(0);
+          next = NULL;
         }
         clo = (Scheme_Object *)GC_resolve2(next, gc);
       }
diff --git a/racket/src/racket/src/schpriv.h b/racket/src/racket/src/schpriv.h
index 073e4bc89d..a4a2fcd96f 100644
--- a/racket/src/racket/src/schpriv.h
+++ b/racket/src/racket/src/schpriv.h
@@ -183,6 +183,7 @@ THREAD_LOCAL_DECL(extern intptr_t scheme_total_gc_time);
 THREAD_LOCAL_DECL(extern int scheme_cont_capture_count);
 THREAD_LOCAL_DECL(extern int scheme_continuation_application_count);
 THREAD_LOCAL_DECL(extern struct Scheme_Prefix *scheme_prefix_finalize);
+THREAD_LOCAL_DECL(extern struct Scheme_Prefix *scheme_inc_prefix_finalize);
 
 int scheme_num_types(void);