diff --git a/esphome/components/alarm_control_panel/alarm_control_panel.cpp b/esphome/components/alarm_control_panel/alarm_control_panel.cpp
index f938155dd3..89c0908a74 100644
--- a/esphome/components/alarm_control_panel/alarm_control_panel.cpp
+++ b/esphome/components/alarm_control_panel/alarm_control_panel.cpp
@@ -8,8 +8,7 @@
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
-namespace esphome {
-namespace alarm_control_panel {
+namespace esphome::alarm_control_panel {
 
 static const char *const TAG = "alarm_control_panel";
 
@@ -115,5 +114,4 @@ void AlarmControlPanel::disarm(optional<std::string> code) {
   call.perform();
 }
 
-}  // namespace alarm_control_panel
-}  // namespace esphome
+}  // namespace esphome::alarm_control_panel
diff --git a/esphome/components/alarm_control_panel/alarm_control_panel.h b/esphome/components/alarm_control_panel/alarm_control_panel.h
index 59ccf0e484..340f15bcd6 100644
--- a/esphome/components/alarm_control_panel/alarm_control_panel.h
+++ b/esphome/components/alarm_control_panel/alarm_control_panel.h
@@ -1,7 +1,5 @@
 #pragma once
 
-#include <map>
-
 #include "alarm_control_panel_call.h"
 #include "alarm_control_panel_state.h"
 
@@ -9,8 +7,7 @@
 #include "esphome/core/entity_base.h"
 #include "esphome/core/log.h"
 
-namespace esphome {
-namespace alarm_control_panel {
+namespace esphome::alarm_control_panel {
 
 enum AlarmControlPanelFeature : uint8_t {
   // Matches Home Assistant values
@@ -141,5 +138,4 @@ class AlarmControlPanel : public EntityBase {
   LazyCallbackManager<void()> ready_callback_{};
 };
 
-}  // namespace alarm_control_panel
-}  // namespace esphome
+}  // namespace esphome::alarm_control_panel
diff --git a/esphome/components/alarm_control_panel/alarm_control_panel_call.cpp b/esphome/components/alarm_control_panel/alarm_control_panel_call.cpp
index 7bb9b9989c..5e98d58368 100644
--- a/esphome/components/alarm_control_panel/alarm_control_panel_call.cpp
+++ b/esphome/components/alarm_control_panel/alarm_control_panel_call.cpp
@@ -4,8 +4,7 @@
 
 #include "esphome/core/log.h"
 
-namespace esphome {
-namespace alarm_control_panel {
+namespace esphome::alarm_control_panel {
 
 static const char *const TAG = "alarm_control_panel";
 
@@ -99,5 +98,4 @@ void AlarmControlPanelCall::perform() {
   }
 }
 
-}  // namespace alarm_control_panel
-}  // namespace esphome
+}  // namespace esphome::alarm_control_panel
diff --git a/esphome/components/alarm_control_panel/alarm_control_panel_call.h b/esphome/components/alarm_control_panel/alarm_control_panel_call.h
index 034e3142da..cff00900dd 100644
--- a/esphome/components/alarm_control_panel/alarm_control_panel_call.h
+++ b/esphome/components/alarm_control_panel/alarm_control_panel_call.h
@@ -6,8 +6,7 @@
 
 #include "esphome/core/helpers.h"
 
-namespace esphome {
-namespace alarm_control_panel {
+namespace esphome::alarm_control_panel {
 
 class AlarmControlPanel;
 
@@ -36,5 +35,4 @@ class AlarmControlPanelCall {
   void validate_();
 };
 
-}  // namespace alarm_control_panel
-}  // namespace esphome
+}  // namespace esphome::alarm_control_panel
diff --git a/esphome/components/alarm_control_panel/alarm_control_panel_state.cpp b/esphome/components/alarm_control_panel/alarm_control_panel_state.cpp
index abe6f51995..862c620497 100644
--- a/esphome/components/alarm_control_panel/alarm_control_panel_state.cpp
+++ b/esphome/components/alarm_control_panel/alarm_control_panel_state.cpp
@@ -1,7 +1,6 @@
 #include "alarm_control_panel_state.h"
 
-namespace esphome {
-namespace alarm_control_panel {
+namespace esphome::alarm_control_panel {
 
 const LogString *alarm_control_panel_state_to_string(AlarmControlPanelState state) {
   switch (state) {
@@ -30,5 +29,4 @@ const LogString *alarm_control_panel_state_to_string(AlarmControlPanelState stat
   }
 }
 
-}  // namespace alarm_control_panel
-}  // namespace esphome
+}  // namespace esphome::alarm_control_panel
diff --git a/esphome/components/alarm_control_panel/alarm_control_panel_state.h b/esphome/components/alarm_control_panel/alarm_control_panel_state.h
index ad16222dc0..dd0b91f064 100644
--- a/esphome/components/alarm_control_panel/alarm_control_panel_state.h
+++ b/esphome/components/alarm_control_panel/alarm_control_panel_state.h
@@ -3,8 +3,7 @@
 #include <cstdint>
 #include "esphome/core/log.h"
 
-namespace esphome {
-namespace alarm_control_panel {
+namespace esphome::alarm_control_panel {
 
 enum AlarmControlPanelState : uint8_t {
   ACP_STATE_DISARMED = 0,
@@ -25,5 +24,4 @@ enum AlarmControlPanelState : uint8_t {
  */
 const LogString *alarm_control_panel_state_to_string(AlarmControlPanelState state);
 
-}  // namespace alarm_control_panel
-}  // namespace esphome
+}  // namespace esphome::alarm_control_panel
diff --git a/esphome/components/alarm_control_panel/automation.h b/esphome/components/alarm_control_panel/automation.h
index af4a14e27a..ce5ceadb47 100644
--- a/esphome/components/alarm_control_panel/automation.h
+++ b/esphome/components/alarm_control_panel/automation.h
@@ -3,8 +3,7 @@
 #include "esphome/core/automation.h"
 #include "alarm_control_panel.h"
 
-namespace esphome {
-namespace alarm_control_panel {
+namespace esphome::alarm_control_panel {
 
 /// Trigger on any state change
 class StateTrigger : public Trigger<> {
@@ -165,5 +164,4 @@ template<typename... Ts> class AlarmControlPanelCondition : public Condition<Ts.
   AlarmControlPanel *parent_;
 };
 
-}  // namespace alarm_control_panel
-}  // namespace esphome
+}  // namespace esphome::alarm_control_panel
diff --git a/esphome/components/text_sensor/text_sensor.cpp b/esphome/components/text_sensor/text_sensor.cpp
index ad1dc0f521..8dfb9dad05 100644
--- a/esphome/components/text_sensor/text_sensor.cpp
+++ b/esphome/components/text_sensor/text_sensor.cpp
@@ -78,8 +78,8 @@ void TextSensor::add_on_raw_state_callback(std::function<void(const std::string
   this->raw_callback_.add(std::move(callback));
 }
 
-std::string TextSensor::get_state() const { return this->state; }
-std::string TextSensor::get_raw_state() const {
+const std::string &TextSensor::get_state() const { return this->state; }
+const std::string &TextSensor::get_raw_state() const {
 // Suppress deprecation warning - get_raw_state() is the replacement API
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
diff --git a/esphome/components/text_sensor/text_sensor.h b/esphome/components/text_sensor/text_sensor.h
index 919bf81c8c..2cd8a65e87 100644
--- a/esphome/components/text_sensor/text_sensor.h
+++ b/esphome/components/text_sensor/text_sensor.h
@@ -37,9 +37,9 @@ class TextSensor : public EntityBase, public EntityBase_DeviceClass {
 #pragma GCC diagnostic pop
 
   /// Getter-syntax for .state.
-  std::string get_state() const;
+  const std::string &get_state() const;
   /// Getter-syntax for .raw_state
-  std::string get_raw_state() const;
+  const std::string &get_raw_state() const;
 
   void publish_state(const std::string &state);
 
diff --git a/esphome/components/web_server/list_entities.cpp b/esphome/components/web_server/list_entities.cpp
index 16b1d1e797..55beed812f 100644
--- a/esphome/components/web_server/list_entities.cpp
+++ b/esphome/components/web_server/list_entities.cpp
@@ -6,8 +6,7 @@
 
 #include "web_server.h"
 
-namespace esphome {
-namespace web_server {
+namespace esphome::web_server {
 
 #ifdef USE_ESP32
 ListEntitiesIterator::ListEntitiesIterator(const WebServer *ws, AsyncEventSource *es) : web_server_(ws), events_(es) {}
@@ -157,6 +156,5 @@ bool ListEntitiesIterator::on_update(update::UpdateEntity *obj) {
 }
 #endif
 
-}  // namespace web_server
-}  // namespace esphome
+}  // namespace esphome::web_server
 #endif
diff --git a/esphome/components/web_server/list_entities.h b/esphome/components/web_server/list_entities.h
index 5d9049b082..56fd91a8c6 100644
--- a/esphome/components/web_server/list_entities.h
+++ b/esphome/components/web_server/list_entities.h
@@ -4,13 +4,13 @@
 #ifdef USE_WEBSERVER
 #include "esphome/core/component.h"
 #include "esphome/core/component_iterator.h"
-namespace esphome {
+namespace esphome::web_server_idf {
 #ifdef USE_ESP32
-namespace web_server_idf {
 class AsyncEventSource;
-}
 #endif
-namespace web_server {
+}  // namespace esphome::web_server_idf
+
+namespace esphome::web_server {
 
 #if !defined(USE_ESP32) && defined(USE_ARDUINO)
 class DeferredUpdateEventSource;
@@ -99,6 +99,5 @@ class ListEntitiesIterator : public ComponentIterator {
 #endif
 };
 
-}  // namespace web_server
-}  // namespace esphome
+}  // namespace esphome::web_server
 #endif
diff --git a/esphome/components/web_server/ota/ota_web_server.cpp b/esphome/components/web_server/ota/ota_web_server.cpp
index f612aa056c..572c351245 100644
--- a/esphome/components/web_server/ota/ota_web_server.cpp
+++ b/esphome/components/web_server/ota/ota_web_server.cpp
@@ -23,8 +23,7 @@ using PlatformString = std::string;
 using PlatformString = String;
 #endif
 
-namespace esphome {
-namespace web_server {
+namespace esphome::web_server {
 
 static const char *const TAG = "web_server.ota";
 
@@ -236,7 +235,6 @@ void WebServerOTAComponent::setup() {
 
 void WebServerOTAComponent::dump_config() { ESP_LOGCONFIG(TAG, "Web Server OTA"); }
 
-}  // namespace web_server
-}  // namespace esphome
+}  // namespace esphome::web_server
 
 #endif  // USE_WEBSERVER_OTA
diff --git a/esphome/components/web_server/ota/ota_web_server.h b/esphome/components/web_server/ota/ota_web_server.h
index a7170c0e34..53ff99899c 100644
--- a/esphome/components/web_server/ota/ota_web_server.h
+++ b/esphome/components/web_server/ota/ota_web_server.h
@@ -7,8 +7,7 @@
 #include "esphome/components/web_server_base/web_server_base.h"
 #include "esphome/core/component.h"
 
-namespace esphome {
-namespace web_server {
+namespace esphome::web_server {
 
 class WebServerOTAComponent : public ota::OTAComponent {
  public:
@@ -20,7 +19,6 @@ class WebServerOTAComponent : public ota::OTAComponent {
   friend class OTARequestHandler;
 };
 
-}  // namespace web_server
-}  // namespace esphome
+}  // namespace esphome::web_server
 
 #endif  // USE_WEBSERVER_OTA
diff --git a/esphome/components/web_server/server_index_v2.h b/esphome/components/web_server/server_index_v2.h
index e675d81552..b2d204c9e7 100644
--- a/esphome/components/web_server/server_index_v2.h
+++ b/esphome/components/web_server/server_index_v2.h
@@ -6,8 +6,7 @@
 
 #include "esphome/core/hal.h"
 
-namespace esphome {
-namespace web_server {
+namespace esphome::web_server {
 
 const uint8_t INDEX_GZ[] PROGMEM = {
     0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xcd, 0x7d, 0xdb, 0x72, 0xdb, 0xc6, 0xb6, 0xe0, 0xf3,
@@ -644,8 +643,7 @@ const uint8_t INDEX_GZ[] PROGMEM = {
     0x2b, 0x4d, 0x17, 0xb8, 0x87, 0x4c, 0xe9, 0x50, 0x19, 0x14, 0xba, 0x92, 0xde, 0x0a, 0xea, 0x97, 0xce, 0xad, 0x80,
     0x4f, 0xc7, 0xf5, 0xfe, 0x1f, 0xe7, 0xe0, 0x1c, 0x12, 0xcf, 0x89, 0x00, 0x00};
 
-}  // namespace web_server
-}  // namespace esphome
+}  // namespace esphome::web_server
 
 #endif
 #endif
diff --git a/esphome/components/web_server/server_index_v3.h b/esphome/components/web_server/server_index_v3.h
index 39518197a3..8a8ced9153 100644
--- a/esphome/components/web_server/server_index_v3.h
+++ b/esphome/components/web_server/server_index_v3.h
@@ -6,8 +6,7 @@
 
 #include "esphome/core/hal.h"
 
-namespace esphome {
-namespace web_server {
+namespace esphome::web_server {
 
 const uint8_t INDEX_GZ[] PROGMEM = {
     0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xcc, 0xbd, 0xeb, 0x7a, 0x1b, 0xb7, 0xb2, 0x20, 0xfa,
@@ -4048,8 +4047,7 @@ const uint8_t INDEX_GZ[] PROGMEM = {
     0x3b, 0x6c, 0x78, 0x02, 0xa6, 0xdc, 0xb4, 0xe8, 0xee, 0x6a, 0xc5, 0x97, 0x94, 0x7e, 0xd1, 0x9b, 0x83, 0x45, 0xb2,
     0xf4, 0x87, 0xff, 0x07, 0x52, 0xaf, 0x09, 0x6c, 0x30, 0x6a, 0x03, 0x00};
 
-}  // namespace web_server
-}  // namespace esphome
+}  // namespace esphome::web_server
 
 #endif
 #endif
diff --git a/esphome/components/web_server/web_server.cpp b/esphome/components/web_server/web_server.cpp
index df8a5364cf..f613d6bc36 100644
--- a/esphome/components/web_server/web_server.cpp
+++ b/esphome/components/web_server/web_server.cpp
@@ -36,8 +36,7 @@
 #endif
 #endif
 
-namespace esphome {
-namespace web_server {
+namespace esphome::web_server {
 
 static const char *const TAG = "web_server";
 
@@ -45,13 +44,6 @@ static const char *const TAG = "web_server";
 static constexpr size_t PSTR_LOCAL_SIZE = 18;
 #define PSTR_LOCAL(mode_s) ESPHOME_strncpy_P(buf, (ESPHOME_PGM_P) ((mode_s)), PSTR_LOCAL_SIZE - 1)
 
-#ifdef USE_WEBSERVER_PRIVATE_NETWORK_ACCESS
-static const char *const HEADER_PNA_NAME = "Private-Network-Access-Name";
-static const char *const HEADER_PNA_ID = "Private-Network-Access-ID";
-static const char *const HEADER_CORS_REQ_PNA = "Access-Control-Request-Private-Network";
-static const char *const HEADER_CORS_ALLOW_PNA = "Access-Control-Allow-Private-Network";
-#endif
-
 // Parse URL and return match info
 static UrlMatch match_url(const char *url_ptr, size_t url_len, bool only_domain) {
   UrlMatch match{};
@@ -348,7 +340,7 @@ void WebServer::handle_index_request(AsyncWebServerRequest *request) {
 #else
   AsyncWebServerResponse *response = request->beginResponse_P(200, "text/html", INDEX_GZ, sizeof(INDEX_GZ));
 #endif
-  response->addHeader("Content-Encoding", "gzip");
+  response->addHeader(ESPHOME_F("Content-Encoding"), ESPHOME_F("gzip"));
   request->send(response);
 }
 #elif USE_WEBSERVER_VERSION >= 2
@@ -368,10 +360,10 @@ void WebServer::handle_index_request(AsyncWebServerRequest *request) {
 #ifdef USE_WEBSERVER_PRIVATE_NETWORK_ACCESS
 void WebServer::handle_pna_cors_request(AsyncWebServerRequest *request) {
   AsyncWebServerResponse *response = request->beginResponse(200, "");
-  response->addHeader(HEADER_CORS_ALLOW_PNA, "true");
-  response->addHeader(HEADER_PNA_NAME, App.get_name().c_str());
+  response->addHeader(ESPHOME_F("Access-Control-Allow-Private-Network"), ESPHOME_F("true"));
+  response->addHeader(ESPHOME_F("Private-Network-Access-Name"), App.get_name().c_str());
   char mac_s[18];
-  response->addHeader(HEADER_PNA_ID, get_mac_address_pretty_into_buffer(mac_s));
+  response->addHeader(ESPHOME_F("Private-Network-Access-ID"), get_mac_address_pretty_into_buffer(mac_s));
   request->send(response);
 }
 #endif
@@ -385,7 +377,7 @@ void WebServer::handle_css_request(AsyncWebServerRequest *request) {
   AsyncWebServerResponse *response =
       request->beginResponse_P(200, "text/css", ESPHOME_WEBSERVER_CSS_INCLUDE, ESPHOME_WEBSERVER_CSS_INCLUDE_SIZE);
 #endif
-  response->addHeader("Content-Encoding", "gzip");
+  response->addHeader(ESPHOME_F("Content-Encoding"), ESPHOME_F("gzip"));
   request->send(response);
 }
 #endif
@@ -399,7 +391,7 @@ void WebServer::handle_js_request(AsyncWebServerRequest *request) {
   AsyncWebServerResponse *response =
       request->beginResponse_P(200, "text/javascript", ESPHOME_WEBSERVER_JS_INCLUDE, ESPHOME_WEBSERVER_JS_INCLUDE_SIZE);
 #endif
-  response->addHeader("Content-Encoding", "gzip");
+  response->addHeader(ESPHOME_F("Content-Encoding"), ESPHOME_F("gzip"));
   request->send(response);
 }
 #endif
@@ -1841,7 +1833,7 @@ bool WebServer::canHandle(AsyncWebServerRequest *request) const {
   }
 
 #ifdef USE_WEBSERVER_PRIVATE_NETWORK_ACCESS
-  if (method == HTTP_OPTIONS && request->hasHeader(HEADER_CORS_REQ_PNA))
+  if (method == HTTP_OPTIONS && request->hasHeader(ESPHOME_F("Access-Control-Request-Private-Network")))
     return true;
 #endif
 
@@ -1974,7 +1966,7 @@ void WebServer::handleRequest(AsyncWebServerRequest *request) {
 #endif
 
 #ifdef USE_WEBSERVER_PRIVATE_NETWORK_ACCESS
-  if (request->method() == HTTP_OPTIONS && request->hasHeader(HEADER_CORS_REQ_PNA)) {
+  if (request->method() == HTTP_OPTIONS && request->hasHeader(ESPHOME_F("Access-Control-Request-Private-Network"))) {
     this->handle_pna_cors_request(request);
     return;
   }
@@ -2112,6 +2104,5 @@ void WebServer::add_sorting_group(uint64_t group_id, const std::string &group_na
 }
 #endif
 
-}  // namespace web_server
-}  // namespace esphome
+}  // namespace esphome::web_server
 #endif
diff --git a/esphome/components/web_server/web_server.h b/esphome/components/web_server/web_server.h
index 0078146284..b9e852c745 100644
--- a/esphome/components/web_server/web_server.h
+++ b/esphome/components/web_server/web_server.h
@@ -33,8 +33,7 @@ extern const uint8_t ESPHOME_WEBSERVER_JS_INCLUDE[] PROGMEM;
 extern const size_t ESPHOME_WEBSERVER_JS_INCLUDE_SIZE;
 #endif
 
-namespace esphome {
-namespace web_server {
+namespace esphome::web_server {
 
 /// Internal helper struct that is used to parse incoming URLs
 struct UrlMatch {
@@ -616,6 +615,5 @@ class WebServer : public Controller,
 #endif
 };
 
-}  // namespace web_server
-}  // namespace esphome
+}  // namespace esphome::web_server
 #endif
diff --git a/esphome/components/web_server/web_server_v1.cpp b/esphome/components/web_server/web_server_v1.cpp
index cbc25b9dec..e27306ad78 100644
--- a/esphome/components/web_server/web_server_v1.cpp
+++ b/esphome/components/web_server/web_server_v1.cpp
@@ -3,8 +3,7 @@
 
 #if USE_WEBSERVER_VERSION == 1
 
-namespace esphome {
-namespace web_server {
+namespace esphome::web_server {
 
 void write_row(AsyncResponseStream *stream, EntityBase *obj, const std::string &klass, const std::string &action,
                const std::function<void(AsyncResponseStream &stream, EntityBase *obj)> &action_func = nullptr) {
@@ -215,6 +214,5 @@ void WebServer::handle_index_request(AsyncWebServerRequest *request) {
   request->send(stream);
 }
 
-}  // namespace web_server
-}  // namespace esphome
+}  // namespace esphome::web_server
 #endif
diff --git a/esphome/components/web_server_base/web_server_base.h b/esphome/components/web_server_base/web_server_base.h
index 54ec997671..7e95e00f29 100644
--- a/esphome/components/web_server_base/web_server_base.h
+++ b/esphome/components/web_server_base/web_server_base.h
@@ -100,7 +100,7 @@ class WebServerBase : public Component {
     }
     this->server_ = std::make_unique<AsyncWebServer>(this->port_);
     // All content is controlled and created by user - so allowing all origins is fine here.
-    DefaultHeaders::Instance().addHeader("Access-Control-Allow-Origin", "*");
+    DefaultHeaders::Instance().addHeader(ESPHOME_F("Access-Control-Allow-Origin"), ESPHOME_F("*"));
     this->server_->begin();
 
     for (auto *handler : this->handlers_)
diff --git a/esphome/components/wifi/wifi_component.cpp b/esphome/components/wifi/wifi_component.cpp
index 242265344d..5fa894d8f9 100644
--- a/esphome/components/wifi/wifi_component.cpp
+++ b/esphome/components/wifi/wifi_component.cpp
@@ -1523,12 +1523,12 @@ void WiFiComponent::log_and_adjust_priority_for_failed_connect_() {
     return;  // No BSSID to penalize
   }
 
-  // Get SSID for logging
-  std::string ssid;
+  // Get SSID for logging (use pointer to avoid copy)
+  const std::string *ssid = nullptr;
   if (this->retry_phase_ == WiFiRetryPhase::SCAN_CONNECTING && !this->scan_result_.empty()) {
-    ssid = this->scan_result_[0].get_ssid();
+    ssid = &this->scan_result_[0].get_ssid();
   } else if (const WiFiAP *config = this->get_selected_sta_()) {
-    ssid = config->get_ssid();
+    ssid = &config->get_ssid();
   }
 
   // Only decrease priority on the last attempt for this phase
@@ -1548,8 +1548,8 @@ void WiFiComponent::log_and_adjust_priority_for_failed_connect_() {
   }
   char bssid_s[18];
   format_mac_addr_upper(failed_bssid.value().data(), bssid_s);
-  ESP_LOGD(TAG, "Failed " LOG_SECRET("'%s'") " " LOG_SECRET("(%s)") ", priority %d → %d", ssid.c_str(), bssid_s,
-           old_priority, new_priority);
+  ESP_LOGD(TAG, "Failed " LOG_SECRET("'%s'") " " LOG_SECRET("(%s)") ", priority %d → %d",
+           ssid != nullptr ? ssid->c_str() : "", bssid_s, old_priority, new_priority);
 
   // After adjusting priority, check if all priorities are now at minimum
   // If so, clear the vector to save memory and reset for fresh start
diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index b5b8648073..48a2313e2c 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -687,7 +687,7 @@ inline char format_hex_pretty_char(uint8_t v) { return v >= 10 ? 'A' + (v - 10)
 /// Write int8 value to buffer without modulo operations.
 /// Buffer must have at least 4 bytes free. Returns pointer past last char written.
 inline char *int8_to_str(char *buf, int8_t val) {
-  int v = val;
+  int32_t v = val;
   if (v < 0) {
     *buf++ = '-';
     v = -v;
@@ -696,11 +696,11 @@ inline char *int8_to_str(char *buf, int8_t val) {
     *buf++ = '1';  // int8 max is 128, so hundreds digit is always 1
     v -= 100;
     // Must write tens digit (even if 0) after hundreds
-    int tens = v / 10;
+    int32_t tens = v / 10;
     *buf++ = '0' + tens;
     v -= tens * 10;
   } else if (v >= 10) {
-    int tens = v / 10;
+    int32_t tens = v / 10;
     *buf++ = '0' + tens;
     v -= tens * 10;
   }