diff --git a/py/obj.h b/py/obj.h
index 55f2359700..a794e0e958 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -26,6 +26,8 @@
 #ifndef __MICROPY_INCLUDED_PY_OBJ_H__
 #define __MICROPY_INCLUDED_PY_OBJ_H__
 
+#include <stdarg.h>
+
 #include "py/mpconfig.h"
 #include "py/misc.h"
 #include "py/qstr.h"
@@ -622,6 +624,7 @@ mp_obj_t mp_obj_new_exception_arg1(const mp_obj_type_t *exc_type, mp_obj_t arg);
 mp_obj_t mp_obj_new_exception_args(const mp_obj_type_t *exc_type, mp_uint_t n_args, const mp_obj_t *args);
 mp_obj_t mp_obj_new_exception_msg(const mp_obj_type_t *exc_type, const char *msg);
 mp_obj_t mp_obj_new_exception_msg_varg(const mp_obj_type_t *exc_type, const char *fmt, ...); // counts args by number of % symbols in fmt, excluding %%; can only handle void* sizes (ie no float/double!)
+mp_obj_t mp_obj_new_exception_msg_vlist(const mp_obj_type_t *exc_type, const char *fmt, va_list ap); // counts args by number of % symbols in fmt, excluding %%; can only handle void* sizes (ie no float/double!)
 mp_obj_t mp_obj_new_fun_bc(mp_obj_t def_args, mp_obj_t def_kw_args, const byte *code, const mp_uint_t *const_table);
 mp_obj_t mp_obj_new_fun_native(mp_obj_t def_args_in, mp_obj_t def_kw_args, const void *fun_data, const mp_uint_t *const_table);
 mp_obj_t mp_obj_new_fun_viper(mp_uint_t n_args, void *fun_data, mp_uint_t type_sig);
diff --git a/py/objexcept.c b/py/objexcept.c
index c1b992d276..9320b51474 100644
--- a/py/objexcept.c
+++ b/py/objexcept.c
@@ -322,6 +322,14 @@ mp_obj_t mp_obj_new_exception_msg(const mp_obj_type_t *exc_type, const char *msg
 }
 
 mp_obj_t mp_obj_new_exception_msg_varg(const mp_obj_type_t *exc_type, const char *fmt, ...) {
+    va_list ap;
+    va_start(ap, fmt);
+    mp_obj_t exception = mp_obj_new_exception_msg_vlist(exc_type, fmt, ap);
+    va_end(ap);
+    return exception;
+}
+
+mp_obj_t mp_obj_new_exception_msg_vlist(const mp_obj_type_t *exc_type, const char *fmt, va_list ap) {
     // check that the given type is an exception type
     assert(exc_type->make_new == mp_obj_exception_make_new);
 
@@ -354,10 +362,7 @@ mp_obj_t mp_obj_new_exception_msg_varg(const mp_obj_type_t *exc_type, const char
             vstr_t vstr;
             vstr_init_fixed_buf(&vstr, max_len, (char *)str_data);
 
-            va_list ap;
-            va_start(ap, fmt);
             vstr_vprintf(&vstr, fmt, ap);
-            va_end(ap);
 
             str->base.type = &mp_type_str;
             str->hash = qstr_compute_hash(str_data, str->len);
@@ -392,12 +397,9 @@ mp_obj_t mp_obj_new_exception_msg_varg(const mp_obj_type_t *exc_type, const char
                 o->args->items[0] = mp_obj_new_str(fmt, strlen(fmt), false);
             } else {
                 // render exception message and store as .args[0]
-                va_list ap;
                 vstr_t vstr;
                 vstr_init(&vstr, 16);
-                va_start(ap, fmt);
                 vstr_vprintf(&vstr, fmt, ap);
-                va_end(ap);
                 o->args->items[0] = mp_obj_new_str_from_vstr(&mp_type_str, &vstr);
             }
         }
diff --git a/py/runtime.c b/py/runtime.c
index 1177c60c08..ad1228d4d0 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -1466,7 +1466,7 @@ NORETURN void mp_raise_msg(const mp_obj_type_t *exc_type, const char *msg) {
 NORETURN void mp_raise_msg_varg(const mp_obj_type_t *exc_type, const char *fmt, ...) {
     va_list argptr;
     va_start(argptr,fmt);
-    mp_obj_t exception = mp_obj_new_exception_msg_varg(exc_type, fmt, argptr);
+    mp_obj_t exception = mp_obj_new_exception_msg_vlist(exc_type, fmt, argptr);
     va_end(argptr);
     nlr_raise(exception);
 }
@@ -1498,7 +1498,7 @@ NORETURN void mp_raise_ValueError(const char *msg) {
 NORETURN void mp_raise_ValueError_varg(const char *fmt, ...) {
     va_list argptr;
     va_start(argptr,fmt);
-    mp_obj_t exception = mp_obj_new_exception_msg_varg(&mp_type_ValueError, fmt, argptr);
+    mp_obj_t exception = mp_obj_new_exception_msg_vlist(&mp_type_ValueError, fmt, argptr);
     va_end(argptr);
     nlr_raise(exception);
 }
@@ -1510,7 +1510,7 @@ NORETURN void mp_raise_TypeError(const char *msg) {
 NORETURN void mp_raise_TypeError_varg(const char *fmt, ...) {
     va_list argptr;
     va_start(argptr,fmt);
-    mp_obj_t exception = mp_obj_new_exception_msg_varg(&mp_type_TypeError, fmt, argptr);
+    mp_obj_t exception = mp_obj_new_exception_msg_vlist(&mp_type_TypeError, fmt, argptr);
     va_end(argptr);
     nlr_raise(exception);
 }