diff --git a/racket/src/ChezScheme/c/alloc.c b/racket/src/ChezScheme/c/alloc.c
index bd0b50dce1..9df9226641 100644
--- a/racket/src/ChezScheme/c/alloc.c
+++ b/racket/src/ChezScheme/c/alloc.c
@@ -696,11 +696,10 @@ ptr S_fxvector(n) iptr n; {
 }
 
 ptr S_bytevector(n) iptr n; {
-  return S_bytevector2(n, 0);
+  return S_bytevector2(get_thread_context(), n, 0);
 }
 
-ptr S_bytevector2(n, immobile) iptr n; IBOOL immobile; {
-    ptr tc;
+ptr S_bytevector2(tc, n, immobile) ptr tc; iptr n; IBOOL immobile; {
     ptr p; iptr d;
 
     if (n == 0) return S_G.null_bytevector;
@@ -708,8 +707,6 @@ ptr S_bytevector2(n, immobile) iptr n; IBOOL immobile; {
     if ((uptr)n > (uptr)maximum_bytevector_length)
         S_error("", "invalid bytevector size request");
 
-    tc = get_thread_context();
-
     d = size_bytevector(n);
     if (immobile)
       find_room(tc, space_immobile_data, 0, type_typed_object, d, p);
diff --git a/racket/src/ChezScheme/c/externs.h b/racket/src/ChezScheme/c/externs.h
index 02a3cdffff..5d52cc11d4 100644
--- a/racket/src/ChezScheme/c/externs.h
+++ b/racket/src/ChezScheme/c/externs.h
@@ -87,7 +87,7 @@ extern ptr S_vector_in PROTO((ptr tc, ISPC s, IGEN g, iptr n));
 extern ptr S_vector PROTO((iptr n));
 extern ptr S_fxvector PROTO((iptr n));
 extern ptr S_bytevector PROTO((iptr n));
-extern ptr S_bytevector2 PROTO((iptr n, IBOOL immobile));
+extern ptr S_bytevector2 PROTO((ptr tc, iptr n, IBOOL immobile));
 extern ptr S_null_immutable_vector PROTO((void));
 extern ptr S_null_immutable_fxvector PROTO((void));
 extern ptr S_null_immutable_bytevector PROTO((void));
diff --git a/racket/src/ChezScheme/c/flushcache.c b/racket/src/ChezScheme/c/flushcache.c
index d273363087..6ddcfbef2b 100644
--- a/racket/src/ChezScheme/c/flushcache.c
+++ b/racket/src/ChezScheme/c/flushcache.c
@@ -27,10 +27,10 @@ typedef struct {
 
 static uptr max_gap;
 
-static ptr make_mod_range PROTO((uptr start, uptr end));
+static ptr make_mod_range PROTO((ptr tc, uptr start, uptr end));
 
-static ptr make_mod_range(uptr start, uptr end) {
-  ptr bv = S_bytevector(sizeof(mod_range));
+static ptr make_mod_range(ptr tc, uptr start, uptr end) {
+  ptr bv = S_bytevector2(tc, sizeof(mod_range), 0);
   mod_range_start(bv) = start;
   mod_range_end(bv) = end;
   return bv;
@@ -59,7 +59,7 @@ void S_record_code_mod(ptr tc, uptr addr, uptr bytes) {
 #ifdef DEBUG
       printf("  record_code_mod new range %x to %x\n", addr, end); fflush(stdout);
 #endif
-  CODERANGESTOFLUSH(tc) = S_cons_in(tc, space_new, 0, make_mod_range(addr, end), ls);
+  CODERANGESTOFLUSH(tc) = S_cons_in(tc, space_new, 0, make_mod_range(tc, addr, end), ls);
   return;
 }
 
diff --git a/racket/src/ChezScheme/c/prim5.c b/racket/src/ChezScheme/c/prim5.c
index 335e69ac5f..e49ed541cd 100644
--- a/racket/src/ChezScheme/c/prim5.c
+++ b/racket/src/ChezScheme/c/prim5.c
@@ -211,7 +211,7 @@ static ptr s_box_immobile(p) ptr p; {
 }
 
 static ptr s_make_immobile_bytevector(uptr len) {
-  ptr b = S_bytevector2(len, 1);
+  ptr b = S_bytevector2(get_thread_context(), len, 1);
   S_immobilize_object(b);
   return b;
 }