diff --git a/racket/src/racket/sgc/sgc.h b/racket/src/racket/sgc/sgc.h
index 3432088f12..888f5fd51b 100644
--- a/racket/src/racket/sgc/sgc.h
+++ b/racket/src/racket/sgc/sgc.h
@@ -20,8 +20,8 @@ extern "C" {
 
 SGC_EXTERN void GC_add_roots(void *start, void *end);
 
-SGC_EXTERN void (*GC_start_collect_callback)(void);
-SGC_EXTERN void (*GC_end_collect_callback)(void);
+SGC_EXTERN void (*GC_collect_start_callback)(void);
+SGC_EXTERN void (*GC_collect_end_callback)(void);
 SGC_EXTERN void (*GC_custom_finalize)(void);
 SGC_EXTERN void (*GC_out_of_memory)(void);
 
diff --git a/racket/src/racket/src/syntax.c b/racket/src/racket/src/syntax.c
index 0a88a9c781..60a03d9cea 100644
--- a/racket/src/racket/src/syntax.c
+++ b/racket/src/racket/src/syntax.c
@@ -3911,6 +3911,7 @@ Scheme_Object *scheme_stx_lookup_w_nominal(Scheme_Object *o, Scheme_Object *phas
   int cache_pos;
 
   STX_ASSERT(SCHEME_STXP(o));
+  STX_ASSERT(nominal_name || (!src_phase && !nominal_src_phase));
 
   orig_name = SCHEME_STX_VAL(o);