diff --git a/py/argcheck.c b/py/argcheck.c
index d639d08fb1..28bce8a86d 100644
--- a/py/argcheck.c
+++ b/py/argcheck.c
@@ -33,7 +33,7 @@
 void mp_arg_check_num(size_t n_args, size_t n_kw, size_t n_args_min, size_t n_args_max, bool takes_kw) {
     // NOTE(tannewt): This prevents this function from being optimized away.
     // Without it, functions can crash when reading invalid args.
-    asm ("");
+    __asm volatile ("");
     // TODO maybe take the function name as an argument so we can print nicer error messages
 
     if (n_kw && !takes_kw) {
diff --git a/py/stackctrl.c b/py/stackctrl.c
index 1c46a94347..d9969b56c2 100644
--- a/py/stackctrl.c
+++ b/py/stackctrl.c
@@ -32,7 +32,7 @@
 
 void mp_stack_ctrl_init(void) {
     // Force routine to not be inlined. Better guarantee than MP_NOINLINE for -flto.
-    asm("");
+    __asm volatile ("");
     volatile int stack_dummy;
     MP_STATE_THREAD(stack_top) = (char*)&stack_dummy;
 }
@@ -44,7 +44,7 @@ void mp_stack_set_top(void *top) {
 mp_uint_t mp_stack_usage(void) {
     // Assumes descending stack
     // Force routine to not be inlined. Better guarantee than MP_NOINLINE for -flto.
-    asm("");
+    __asm volatile ("");
     volatile int stack_dummy;
     return MP_STATE_THREAD(stack_top) - (char*)&stack_dummy;
 }