diff --git a/esphome/components/text_sensor/filter.cpp b/esphome/components/text_sensor/filter.cpp
index a6d0ae0c93..52c2bd394e 100644
--- a/esphome/components/text_sensor/filter.cpp
+++ b/esphome/components/text_sensor/filter.cpp
@@ -62,7 +62,10 @@ optional<std::string> AppendFilter::new_value(std::string value) {
 }
 
 // Prepend
-optional<std::string> PrependFilter::new_value(std::string value) { return this->prefix_ + value; }
+optional<std::string> PrependFilter::new_value(std::string value) {
+  value.insert(0, this->prefix_.c_str(), this->prefix_.size());
+  return value;
+}
 
 // Substitute
 SubstituteFilter::SubstituteFilter(const std::initializer_list<Substitution> &substitutions)