diff --git a/esphome/components/esp8266/preferences.cpp b/esphome/components/esp8266/preferences.cpp
index 7b6b7c73d9..4d1e82ece0 100644
--- a/esphome/components/esp8266/preferences.cpp
+++ b/esphome/components/esp8266/preferences.cpp
@@ -149,11 +149,11 @@ class ESP8266PreferenceBackend : public ESPPreferenceBackend {
 
     if (buffer_size <= PREF_BUFFER_WORDS) {
       buffer = stack_buffer;
-      memset(buffer, 0, buffer_size * sizeof(uint32_t));
     } else {
       heap_buffer = make_unique<uint32_t[]>(buffer_size);
       buffer = heap_buffer.get();
     }
+    memset(buffer, 0, buffer_size * sizeof(uint32_t));
 
     memcpy(buffer, data, len);
     buffer[this->length_words] = calculate_crc(buffer, buffer + this->length_words, this->type);