diff --git a/esphome/core/hal/hal_esp8266.h b/esphome/core/hal/hal_esp8266.h
index b6e3b1ee3c..976b697686 100644
--- a/esphome/core/hal/hal_esp8266.h
+++ b/esphome/core/hal/hal_esp8266.h
@@ -66,6 +66,8 @@ __attribute__((always_inline)) inline void arch_init() {}
 __attribute__((always_inline)) inline uint32_t arch_get_cpu_cycle_count() { return esp_get_cycle_count(); }
 __attribute__((always_inline)) inline uint32_t arch_get_cpu_freq_hz() { return F_CPU; }
 
+uint32_t arch_get_cpu_cycle_count();
+
 }  // namespace esphome
 
 #endif  // USE_ESP8266