diff --git a/esphome/components/esp32/core.cpp b/esphome/components/esp32/core.cpp
index 1bb34295cd..b9ae871abf 100644
--- a/esphome/components/esp32/core.cpp
+++ b/esphome/components/esp32/core.cpp
@@ -23,7 +23,7 @@ namespace esphome {
 
 void HOT yield() { vPortYield(); }
 uint32_t IRAM_ATTR HOT millis() { return (uint32_t) (esp_timer_get_time() / 1000ULL); }
-uint64_t HOT millis_64() { return esp_timer_get_time() / 1000ULL; }
+uint64_t HOT millis_64() { return static_cast<uint64_t>(esp_timer_get_time()) / 1000ULL; }
 void HOT delay(uint32_t ms) { vTaskDelay(ms / portTICK_PERIOD_MS); }
 uint32_t IRAM_ATTR HOT micros() { return (uint32_t) esp_timer_get_time(); }
 void IRAM_ATTR HOT delayMicroseconds(uint32_t us) { delay_microseconds_safe(us); }