diff --git a/esphome/components/sensor/filter.cpp b/esphome/components/sensor/filter.cpp
index 0e52f9d94f..4863c00a29 100644
--- a/esphome/components/sensor/filter.cpp
+++ b/esphome/components/sensor/filter.cpp
@@ -53,11 +53,13 @@ optional<float> SlidingWindowFilter::new_value(float value) {
     // Buffer not yet full - just append
     this->window_.push_back(value);
     this->window_count_++;
-    this->window_head_ = this->window_count_ % this->window_size_;
   } else {
     // Buffer full - overwrite oldest value (ring buffer)
     this->window_[this->window_head_] = value;
-    this->window_head_ = (this->window_head_ + 1) % this->window_size_;
+    this->window_head_++;
+    if (this->window_head_ >= this->window_size_) {
+      this->window_head_ = 0;
+    }
   }
 
   // Check if we should send a result