diff --git a/src/vm_loader.c b/src/vm_loader.c
index 0fd8b6b33..d0046f345 100644
--- a/src/vm_loader.c
+++ b/src/vm_loader.c
@@ -51,7 +51,7 @@ VM_DEFINE_LOADER (load_integer, "load-integer")
       long val = 0;
       while (len-- > 0)
 	val = (val << 8) + FETCH ();
-      SYNC_BEFORE_GC ();
+      SYNC_REGISTER ();
       PUSH (scm_from_ulong (val));
       NEXT;
     }
@@ -64,7 +64,7 @@ VM_DEFINE_LOADER (load_number, "load-number")
   size_t len;
 
   FETCH_LENGTH (len);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   PUSH (scm_string_to_number (scm_from_locale_stringn ((char *)ip, len),
 			      SCM_UNDEFINED /* radix = 10 */));
   /* Was: scm_istring2number (ip, len, 10)); */
@@ -76,7 +76,7 @@ VM_DEFINE_LOADER (load_string, "load-string")
 {
   size_t len;
   FETCH_LENGTH (len);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   PUSH (scm_from_locale_stringn ((char *)ip, len));
   /* Was: scm_makfromstr (ip, len, 0) */
   ip += len;
@@ -87,7 +87,7 @@ VM_DEFINE_LOADER (load_symbol, "load-symbol")
 {
   size_t len;
   FETCH_LENGTH (len);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   PUSH (scm_from_locale_symboln ((char *)ip, len));
   ip += len;
   NEXT;
@@ -97,7 +97,7 @@ VM_DEFINE_LOADER (load_keyword, "load-keyword")
 {
   size_t len;
   FETCH_LENGTH (len);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   PUSH (scm_from_locale_keywordn ((char *)ip, len));
   ip += len;
   NEXT;
@@ -107,7 +107,7 @@ VM_DEFINE_LOADER (load_module, "load-module")
 {
   size_t len;
   FETCH_LENGTH (len);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   PUSH (scm_c_lookup_env (scm_from_locale_symboln ((char *)ip, len)));
   ip += len;
   NEXT;
@@ -120,7 +120,7 @@ VM_DEFINE_LOADER (load_program, "load-program")
   struct scm_program *p;
 
   FETCH_LENGTH (len);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   prog = scm_c_make_program (ip, len, program);
   p = SCM_PROGRAM_DATA (prog);
   ip += len;
@@ -188,7 +188,7 @@ VM_DEFINE_INSTRUCTION (link_now, "link-now", 0, 1, 1)
 {
   SCM sym;
   POP (sym);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   PUSH (scm_lookup (sym)); /* might longjmp */
   NEXT;
 }
@@ -198,7 +198,7 @@ VM_DEFINE_INSTRUCTION (link_later, "link-later", 0, 2, 1)
   SCM modname, sym;
   POP (sym);
   POP (modname);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   PUSH (scm_cons (modname, sym));
   NEXT;
 }
@@ -209,11 +209,11 @@ VM_DEFINE_LOADER (define, "define")
   size_t len;
 
   FETCH_LENGTH (len);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   sym = scm_from_locale_symboln ((char *)ip, len);
   ip += len;
 
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   PUSH (scm_sym2var (sym, scm_current_module_lookup_closure (), SCM_BOOL_T));
   NEXT;
 }
@@ -224,7 +224,7 @@ VM_DEFINE_LOADER (late_bind, "late-bind")
   size_t len;
 
   FETCH_LENGTH (len);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   sym = scm_from_locale_symboln ((char *)ip, len);
   ip += len;
 
diff --git a/src/vm_scheme.c b/src/vm_scheme.c
index 2408f6415..d074abd87 100644
--- a/src/vm_scheme.c
+++ b/src/vm_scheme.c
@@ -89,7 +89,7 @@ VM_DEFINE_FUNCTION (eqv, "eqv?", 2)
     RETURN (SCM_BOOL_T);
   if (SCM_IMP (x) || SCM_IMP (y))
     RETURN (SCM_BOOL_F);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   RETURN (scm_eqv_p (x, y));
 }
 
@@ -100,7 +100,7 @@ VM_DEFINE_FUNCTION (equal, "equal?", 2)
     RETURN (SCM_BOOL_T);
   if (SCM_IMP (x) || SCM_IMP (y))
     RETURN (SCM_BOOL_F);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   RETURN (scm_equal_p (x, y));
 }
 
@@ -212,7 +212,7 @@ VM_DEFINE_FUNCTION (ge, "ge?", 2)
       if (SCM_FIXABLE (n))			\
 	RETURN (SCM_I_MAKINUM (n));		\
     }						\
-  SYNC_BEFORE_GC ();                            \
+  SYNC_REGISTER ();                            \
   RETURN (SEXP);				\
 }
 
@@ -226,7 +226,7 @@ VM_DEFINE_FUNCTION (ge, "ge?", 2)
       if (SCM_FIXABLE (n))				\
 	RETURN (SCM_I_MAKINUM (n));			\
     }							\
-  SYNC_BEFORE_GC ();                                    \
+  SYNC_REGISTER ();                                    \
   RETURN (SFUNC (x, y));				\
 }
 
@@ -243,35 +243,35 @@ VM_DEFINE_FUNCTION (sub, "sub", 2)
 VM_DEFINE_FUNCTION (mul, "mul", 2)
 {
   ARGS2 (x, y);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   RETURN (scm_product (x, y));
 }
 
 VM_DEFINE_FUNCTION (div, "div", 2)
 {
   ARGS2 (x, y);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   RETURN (scm_divide (x, y));
 }
 
 VM_DEFINE_FUNCTION (quo, "quo", 2)
 {
   ARGS2 (x, y);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   RETURN (scm_quotient (x, y));
 }
 
 VM_DEFINE_FUNCTION (rem, "rem", 2)
 {
   ARGS2 (x, y);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   RETURN (scm_remainder (x, y));
 }
 
 VM_DEFINE_FUNCTION (mod, "mod", 2)
 {
   ARGS2 (x, y);
-  SYNC_BEFORE_GC ();
+  SYNC_REGISTER ();
   RETURN (scm_modulo (x, y));
 }
 
diff --git a/src/vm_system.c b/src/vm_system.c
index d1b9f61aa..4125a456c 100644
--- a/src/vm_system.c
+++ b/src/vm_system.c
@@ -480,6 +480,7 @@ VM_DEFINE_INSTRUCTION (call, "call", 1, -1, 1)
       SCM args;
       POP_LIST (nargs);
       POP (args);
+      SYNC_REGISTER ();
       *sp = scm_apply (x, args, SCM_EOL);
       NEXT;
     }
@@ -601,6 +602,7 @@ VM_DEFINE_INSTRUCTION (tail_call, "tail-call", 1, -1, 1)
       SCM args;
       POP_LIST (nargs);
       POP (args);
+      SYNC_REGISTER ();
       *sp = scm_apply (x, args, SCM_EOL);
       goto vm_return;
     }