diff --git a/core/embed/extmod/modtrezorio/modtrezorio-poll.h b/core/embed/extmod/modtrezorio/modtrezorio-poll.h
index e2fe33442..5fa1508f5 100644
--- a/core/embed/extmod/modtrezorio/modtrezorio-poll.h
+++ b/core/embed/extmod/modtrezorio/modtrezorio-poll.h
@@ -52,7 +52,15 @@ STATIC mp_obj_t mod_trezorio_poll(mp_obj_t ifaces, mp_obj_t list_ref,
     mp_raise_TypeError("invalid list_ref");
   }
 
-  const mp_uint_t timeout = trezor_obj_get_uint(timeout_ms);
+  // The value `timeout_ms` can be negative in a minority of cases, indicating a
+  // deadline overrun. This is not a problem because we use the `timeout` only
+  // to calculate a `deadline`, and having deadline in the past works fine
+  // (except when it overflows, but the code misbehaves near the overflow
+  // anyway). Instead of bothering to correct the negative value in Python, we
+  // just coerce it to an uint. Deliberately assigning *get_int* to *uint_t*
+  // will give us C's wrapping unsigned overflow behavior, and the `deadline`
+  // result will come out correct.
+  const mp_uint_t timeout = trezor_obj_get_int(timeout_ms);
   const mp_uint_t deadline = mp_hal_ticks_ms() + timeout;
   mp_obj_iter_buf_t iterbuf = {0};
 
diff --git a/core/embed/extmod/trezorobj.h b/core/embed/extmod/trezorobj.h
index e9d59f105..af3289aff 100644
--- a/core/embed/extmod/trezorobj.h
+++ b/core/embed/extmod/trezorobj.h
@@ -52,6 +52,9 @@ static inline mp_int_t trezor_obj_get_int(mp_obj_t obj) {
 static inline mp_uint_t trezor_obj_get_uint(mp_obj_t obj) {
   if (MP_OBJ_IS_SMALL_INT(obj)) {
     mp_int_t i = MP_OBJ_SMALL_INT_VALUE(obj);
+    if (i < 0) {
+      mp_raise_TypeError("value is negative");
+    }
     mp_uint_t u = i;
     return u;
   } else if (MP_OBJ_IS_TYPE(obj, &mp_type_int)) {
@@ -78,6 +81,9 @@ static inline uint8_t trezor_obj_get_uint8(mp_obj_t obj) {
 static inline uint64_t trezor_obj_get_uint64(mp_const_obj_t obj) {
   if (MP_OBJ_IS_SMALL_INT(obj)) {
     mp_int_t i = MP_OBJ_SMALL_INT_VALUE(obj);
+    if (i < 0) {
+      mp_raise_TypeError("value is negative");
+    }
     mp_uint_t u = i;
     return u;
   } else if (MP_OBJ_IS_TYPE(obj, &mp_type_int)) {