diff --git a/esphome/components/esp32/core.cpp b/esphome/components/esp32/core.cpp
index 501dd7d2eaf..1bb34295cd5 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() / 1000; }
+uint64_t HOT millis_64() { return 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); }
diff --git a/esphome/core/scheduler.h b/esphome/core/scheduler.h
index c61bd40f7c1..757f60c2ce3 100644
--- a/esphome/core/scheduler.h
+++ b/esphome/core/scheduler.h
@@ -120,10 +120,10 @@ class Scheduler {
   /// Get 64-bit millisecond timestamp (handles 32-bit millis() rollover)
   uint64_t millis_64() { return esphome::millis_64(); }
 
-  // Calculate when the next scheduled item should run
-  // @param now On ESP32, unused (native 64-bit); on other platforms, extended to 64-bit via rollover tracking
-  // Returns the time in milliseconds until the next scheduled item, or nullopt if no items
-  // This method performs cleanup of removed items before checking the schedule
+  // Calculate when the next scheduled item should run.
+  // @param now On ESP32, unused for 64-bit extension (native); on other platforms, extended to 64-bit via rollover.
+  // Returns the time in milliseconds until the next scheduled item, or nullopt if no items.
+  // This method performs cleanup of removed items before checking the schedule.
   // IMPORTANT: This method should only be called from the main thread (loop task).
   optional<uint32_t> next_schedule_in(uint32_t now);