diff --git a/src/StringIndexer.cpp b/src/StringIndexer.cpp
index a535fed..45144d8 100644
--- a/src/StringIndexer.cpp
+++ b/src/StringIndexer.cpp
@@ -1,3 +1,4 @@
 #include "StringIndexer.h"
 
-std::map<StringIndexer::index_t, StringIndexer::StringCounter> StringIndexer::strings;
+StringIndexer::Strings StringIndexer::strings;
+
diff --git a/src/StringIndexer.h b/src/StringIndexer.h
index bdb2da4..ba51e9b 100644
--- a/src/StringIndexer.h
+++ b/src/StringIndexer.h
@@ -1,6 +1,9 @@
 // vim: ts=2 sw=2 expandtab
 #pragma once
+#include <assert.h>
 #include <map>
+#include <unordered_map>
+#include "TinyString.h"
 #include <string>
 #include <string.h>
 
@@ -10,9 +13,11 @@
  */
 class StringIndexer
 {
+  private:
+
   class StringCounter
   {
-    std::string str;
+    TinyString str;
     uint8_t used=0;
     friend class StringIndexer;
 
@@ -29,13 +34,13 @@ class StringIndexer
   public:
     using index_t = uint8_t;
 
-   static const std::string& str(const index_t& index)
-    {
-      static std::string dummy;
-      const auto& it=strings.find(index);
-      if (it == strings.end()) return dummy;
-      return it->second.str;
-    }
+   static const TinyString& str(const index_t& index)
+   {
+     static TinyString dummy;
+     const auto& it=strings.find(index);
+     if (it == strings.end()) return dummy;
+     return it->second.str;
+   }
 
     static void use(const index_t& index)
     {
@@ -77,7 +82,7 @@ class StringIndexer
       {
         if (strings.find(index)==strings.end())
         {
-          strings[index].str = std::string(str, len);
+          strings[index].str = TinyString(str, len);
           strings[index].used++;
           // Serial << "Creating index " << index << " for (" << strings[index].str.c_str() << ") len=" << len << endl;
           return index;
@@ -86,7 +91,9 @@ class StringIndexer
       return 0;  // TODO out of indexes
     }
 
-    static std::map<index_t, StringCounter> strings;
+    using Strings = std::unordered_map<index_t, StringCounter>;
+
+    static Strings strings;
 };
 
 class IndexedString
@@ -103,7 +110,7 @@ class IndexedString
       index=StringIndexer::strToIndex(str, len);
     }
 
-    IndexedString(const std::string& str) : IndexedString(str.c_str(), str.length()) {};
+    IndexedString(const TinyString& str) : IndexedString(str.c_str(), str.length()) {};
 
     ~IndexedString() { StringIndexer::release(index); }
 
@@ -124,7 +131,7 @@ class IndexedString
       return i1.index == i2.index;
     }
 
-    const std::string& str() const { return StringIndexer::str(index); }
+    const TinyString& str() const { return StringIndexer::str(index); }
 
     const StringIndexer::index_t& getIndex() const { return index; }
 
diff --git a/src/TinyMqtt.cpp b/src/TinyMqtt.cpp
index 9767f97..bda2846 100644
--- a/src/TinyMqtt.cpp
+++ b/src/TinyMqtt.cpp
@@ -52,7 +52,7 @@ MqttClient::MqttClient(MqttBroker* local_broker, TcpClient* new_client)
 #endif
 }
 
-MqttClient::MqttClient(MqttBroker* local_broker, const std::string& id)
+MqttClient::MqttClient(MqttBroker* local_broker, const TinyString& id)
   : local_broker(local_broker), clientId(id)
 {
   alive = 0;
@@ -97,7 +97,7 @@ void MqttClient::connect(MqttBroker* local)
   local_broker = local;
 }
 
-void MqttClient::connect(std::string broker, uint16_t port, uint16_t ka)
+void MqttClient::connect(TinyString broker, uint16_t port, uint16_t ka)
 {
   debug("MqttClient::connect_to_host " << broker << ':' << port);
   keep_alive = ka;
@@ -128,7 +128,7 @@ void MqttBroker::addClient(MqttClient* client)
   clients.push_back(client);
 }
 
-void MqttBroker::connect(const std::string& host, uint16_t port)
+void MqttBroker::connect(const TinyString& host, uint16_t port)
 {
   debug("MqttBroker::connect");
   if (remote_broker == nullptr) remote_broker = new MqttClient;
@@ -461,7 +461,7 @@ void MqttClient::processMessage(MqttMessage* mesg)
 
       // ClientId
       mesg->getString(payload, len);
-      clientId = std::string(payload, len);
+      clientId = TinyString(payload, len);
       payload += len;
 
       if (mqtt_flags & FlagWill)  // Will topic
@@ -539,11 +539,11 @@ void MqttClient::processMessage(MqttMessage* mesg)
         payload = header+2;
 
         debug("un/subscribe loop");
-        std::string qoss;
+        TinyString qoss;
         while(payload < mesg->end())
         {
           mesg->getString(payload, len);  // Topic
-          debug( "  topic (" << std::string(payload, len) << ')');
+          debug( "  topic (" << TinyString(payload, len) << ')');
           // subscribe(Topic(payload, len));
           Topic topic(payload, len);
 
@@ -597,7 +597,7 @@ void MqttClient::processMessage(MqttMessage* mesg)
         #if TINY_MQTT_DEBUG
           Console << "Received Publish (" << published.str().c_str() << ") size=" << (int)len << endl;
         #endif
-        // << '(' << std::string(payload, len).c_str() << ')'  << " msglen=" << mesg->length() << endl;
+        // << '(' << TinyString(payload, len).c_str() << ')'  << " msglen=" << mesg->length() << endl;
         if (qos) payload+=2;  // ignore packet identifier if any
         len=mesg->end()-payload;
         // TODO reset DUP
@@ -889,7 +889,7 @@ void MqttMessage::hexdump(const char* prefix) const
   (void)prefix;
 #if TINY_MQTT_DEBUG
   if (TinyMqtt::debug<2) return;
-  static std::map<Type, std::string> tts={
+  static std::map<Type, TinyString> tts={
     { Connect, "Connect" },
     { ConnAck, "Connack" },
     { Publish, "Publish" },
@@ -902,7 +902,7 @@ void MqttMessage::hexdump(const char* prefix) const
     { PingResp, "Pingresp" },
     { Disconnect, "Disconnect" }
   };
-  std::string t("Unknown");
+  TinyString t("Unknown");
   Type typ=static_cast<Type>(buffer[0] & 0xF0);
   if (tts.find(typ) != tts.end())
     t=tts[typ];
@@ -919,7 +919,7 @@ void MqttMessage::hexdump(const char* prefix) const
   const char* hex_to_str = " | ";
   const char* separator = hex_to_str;
   const char* half_sep = " - ";
-  std::string ascii;
+  TinyString ascii;
 
   Console << prefix << " size(" << buffer.size() << "), state=" << state << endl;
 
diff --git a/src/TinyMqtt.h b/src/TinyMqtt.h
index c67f236..6791ff3 100644
--- a/src/TinyMqtt.h
+++ b/src/TinyMqtt.h
@@ -71,9 +71,10 @@ enum __attribute__((packed)) MqttError
 class Topic : public IndexedString
 {
   public:
+    Topic(const TinyString& m) : IndexedString(m){}
     Topic(const char* s, uint8_t len) : IndexedString(s,len){}
     Topic(const char* s) : Topic(s, strlen(s)) {}
-    Topic(const std::string s) : Topic(s.c_str(), s.length()){};
+    // Topic(const TinyString s) : Topic(s.c_str(), s.length()){};
 
     const char* c_str() const { return str().c_str(); }
 
@@ -122,7 +123,7 @@ class MqttMessage
     void incoming(char byte);
     void add(char byte) { incoming(byte); }
     void add(const char* p, size_t len, bool addLength=true );
-    void add(const std::string& s) { add(s.c_str(), s.length()); }
+    void add(const TinyString& s) { add(s.c_str(), s.length()); }
     void add(const Topic& t) { add(t.str()); }
     const char* end() const { return &buffer[0]+buffer.size(); }
     const char* getVHeader() const { return &buffer[vheader]; }
@@ -156,7 +157,7 @@ class MqttMessage
   private:
     void encodeLength();
 
-    std::string buffer;
+    TinyString buffer;
     uint8_t vheader;
     uint16_t size;  // bytes left to receive
     State state;
@@ -181,13 +182,13 @@ class MqttClient
 
     /** Constructor. Broker is the adress of a local broker if not null
         If you want to connect elsewhere, leave broker null and use connect() **/
-    MqttClient(MqttBroker* broker = nullptr, const std::string& id = TINY_MQTT_DEFAULT_CLIENT_ID);
-    MqttClient(const std::string& id) : MqttClient(nullptr, id){}
+    MqttClient(MqttBroker* broker = nullptr, const TinyString& id = TINY_MQTT_DEFAULT_CLIENT_ID);
+    MqttClient(const TinyString& id) : MqttClient(nullptr, id){}
 
     ~MqttClient();
 
     void connect(MqttBroker* local_broker);
-    void connect(std::string broker, uint16_t port, uint16_t keep_alive = 10);
+    void connect(TinyString broker, uint16_t port, uint16_t keep_alive = 10);
 
     // TODO it seems that connected returns true in tcp mode even if
     // no negociation occurred
@@ -202,8 +203,8 @@ class MqttClient
       if (tcp_client) tcp_client->write(buf, length);
     }
 
-    const std::string& id() const { return clientId; }
-    void id(const std::string& new_id) { clientId = new_id; }
+    const TinyString& id() const { return clientId; }
+    void id(const TinyString& new_id) { clientId = new_id; }
 
     /** Should be called in main loop() */
     void loop();
@@ -221,7 +222,7 @@ class MqttClient
     MqttError publish(const Topic&, const char* payload, size_t pay_length);
     MqttError publish(const Topic& t, const char* payload) { return publish(t, payload, strlen(payload)); }
     MqttError publish(const Topic& t, const String& s) { return publish(t, s.c_str(), s.length()); }
-    MqttError publish(const Topic& t, const std::string& s) { return publish(t,s.c_str(),s.length());}
+    MqttError publish(const Topic& t, const TinyString& s) { return publish(t,s.c_str(),s.length());}
     MqttError publish(const Topic& t) { return publish(t, nullptr, 0);};
 
     MqttError subscribe(Topic topic, uint8_t qos=0);
@@ -232,7 +233,7 @@ class MqttClient
     // TODO seems to be useless
     bool isLocal() const { return tcp_client == nullptr; }
 
-    void dump(std::string indent="")
+    void dump(TinyString indent="")
     {
       (void)indent;
       #if TINY_MQTT_DEBUG
@@ -298,7 +299,7 @@ class MqttClient
 
     TcpClient* tcp_client=nullptr;    // connection to remote broker
     std::set<Topic>  subscriptions;
-    std::string clientId;
+    TinyString clientId;
     CallBack callback = nullptr;
 };
 
@@ -318,12 +319,12 @@ class MqttBroker
     void begin() { server->begin(); }
     void loop();
 
-    void connect(const std::string& host, uint16_t port=1883);
+    void connect(const TinyString& host, uint16_t port=1883);
     bool connected() const { return state == Connected; }
 
     size_t clientsCount() const { return clients.size(); }
 
-    void dump(std::string indent="")
+    void dump(TinyString indent="")
     {
       for(auto client: clients)
         client->dump(indent);
diff --git a/src/TinyString.cpp b/src/TinyString.cpp
new file mode 100644
index 0000000..d114016
--- /dev/null
+++ b/src/TinyString.cpp
@@ -0,0 +1,160 @@
+#include "TinyString.h"
+#include <cstdlib>
+
+const char* TinyString::emptyString = "";
+
+TinyString::TinyString(const char* buffer, uint16_t s)
+{
+  dup(buffer, s);
+}
+
+TinyString::TinyString(int i, int base)
+{
+  reserve(sizeof(int)*8+1);
+  itoa(i, str, base);
+  size_ = strlen(str);
+  free_ -= size_;
+}
+
+TinyString::TinyString(const TinyString& m)
+{
+  copy(m);
+}
+
+TinyString& TinyString::operator=(const TinyString& m)
+{
+  copy(m);
+  return *this;
+}
+
+TinyString& TinyString::operator+=(const char c)
+{
+  push_back(c);
+  return *this;
+}
+
+TinyString& TinyString::operator +=(int i)
+{
+  reserve(size_ + sizeof(int)*3+1);
+  itoa(i, str + size_, 10);
+  int8_t sz = strlen(str+size_);
+  size_ += sz;
+  free_ -= sz;
+  return *this;
+}
+
+void TinyString::concat(const char* buf, uint16_t len)
+{
+  reserve(size_ + len + 1);
+  strcpy(str + size_, buf);
+  size_ += len;
+  free_ -= len;
+}
+
+void TinyString::push_back(const char c)
+{
+  reserve(size_+1, extent);
+  str[size_++] = c;
+  str[size_] = 0;
+  free_--;
+}
+
+void TinyString::erase(uint16_t pos, uint16_t size)
+{
+  if (size == npos) size = size_;
+  if (pos > size_) return;
+  if (pos + size > size_) size = size_ - pos;
+  memmove(str+pos, str+pos+size, size_ - pos + 1);
+  if (size_ == size)
+  {
+    clear();
+  }
+  else
+  {
+    size_ -= size;
+    free_ += size;
+  }
+}
+
+void TinyString::clear()
+{
+  if (size_)
+    free(str);
+  str = const_cast<char*>(emptyString);  // Dangerous str must be left untouched when size_ == 0
+  size_ = 0;
+}
+
+TinyString& TinyString::operator = (const char c)
+{
+  dup(&c, 1);
+  return *this;
+}
+
+TinyString TinyString::substr(uint16_t pos, uint16_t size)
+{
+  if (size == npos) size = size_;
+  if (pos > size_) return TinyString();
+  if (pos + size > size_) size = size_ - pos;
+  return TinyString(str+pos, size);
+}
+
+bool TinyString::starts_with(const char* buf, uint16_t size) const
+{
+  const_iterator it(str);
+  while(size and it != end() and (*it == *buf))
+  {
+    it++;
+    buf++;
+    size--;
+  }
+  return size == 0;
+}
+
+int TinyString::compare(const char* s, uint16_t len) const
+{
+  if (len > size_)
+    return memcmp(str, s, size_ + 1);
+  else
+    return memcmp(str, s, len + 1);
+}
+
+void TinyString::reserve(uint16_t sz, uint8_t extent)
+{
+  if (sz == 0)
+  {
+    clear();
+    return;
+  }
+  if (size_ == 0)
+  {
+    free_ = sz + extent;
+    str = static_cast<char*>(malloc(sz + extent));
+    return;
+  }
+  if ((sz > size_ + free_) or (extent > size_ + free_ - sz))
+  {
+    free_ = sz + extent - size_;
+    str = static_cast<char*>(realloc(str, sz + extent));
+  }
+}
+
+void TinyString::collect()
+{
+  if (size_ > 0 and free_ > 1)
+  {
+    str = static_cast<char*>(realloc(str, size_ + 1));
+    free_ = 1;
+  }
+}
+
+void TinyString::dup(const char* buffer, uint16_t sz, uint8_t extent)
+{
+  reserve(sz + 1, extent);
+  memcpy(str, buffer, sz);
+  str[sz] = 0;
+  if (size_ > sz)
+    free_ += size_ - sz;
+  else
+    free_ -= sz - size_;
+  size_ = sz;
+}
diff --git a/src/TinyString.h b/src/TinyString.h
new file mode 100644
index 0000000..8961407
--- /dev/null
+++ b/src/TinyString.h
@@ -0,0 +1,79 @@
+#pragma once
+#include <Arduino.h>
+#include <assert.h>
+#include <cstdint>
+
+#pragma pack(push, 1)
+
+class TinyString
+{
+  public:
+    using value_type = char;
+    static constexpr uint16_t npos = std::numeric_limits<uint16_t>::max();
+
+    TinyString() = default;
+    TinyString(int, int base=10);
+    TinyString(const TinyString&);
+    TinyString(const char*, uint16_t size);
+    TinyString(const char* s) : TinyString(s, strlen(s)){};
+    TinyString& operator= (const TinyString&);
+    ~TinyString() { clear(); }
+
+    int compare(const char* buf, uint16_t len) const;
+    int compare(const char* buf) const { return compare(buf, strlen(buf)); }
+
+    friend bool operator == (const TinyString& l, const TinyString& r) { return l.compare(r) == 0; }
+
+    friend bool operator < (const TinyString& l, const TinyString& r) { return l.compare(r) <0; }
+
+    const char* c_str() const { return str; }
+    uint16_t length() const { return size_; }
+    uint16_t size() const { return length(); }
+    void concat(const char* buf, uint16_t len);
+
+    bool starts_with(const char* buf, uint16_t len) const;
+    bool starts_with(const char* buf) const { return starts_with(buf, strlen(buf)); }
+
+    TinyString substr(uint16_t pos, uint16_t len = npos);
+
+    char& operator[](uint16_t index) const { assert(index < size_); return str[index]; }
+    TinyString& operator = (const char c);
+    TinyString& operator +=(const char c);
+    TinyString& operator +=(const char* buf) { concat(buf, strlen(buf)); return *this; }
+    TinyString& operator +=(const TinyString& s) { concat(s.str, s.size_); return *this; }
+    TinyString& operator +=(int32_t);
+
+    operator const char*() const { return str; }
+
+    void reserve(uint16_t size) { reserve(size, 0); }
+
+    void erase(uint16_t pos, uint16_t size = npos);
+
+    void dup(const char* buffer, uint16_t size, uint8_t extent = 4);
+
+    void push_back(const char c);
+    void clear();
+
+    using const_iterator = const char*;
+    using iterator = char*;
+    const_iterator cbegin() const { return begin(); }
+    const_iterator cend() const { return end(); }
+    iterator begin() const { return str; }
+    iterator end() const { return str + size_; }
+
+    uint16_t capacity() const { return size_ + free_; }
+    void collect(); // Save memory
+
+  private:
+    void reserve(uint16_t new_size, uint8_t extent);
+    void copy(const TinyString& t) { dup(t.str, t.size_); };
+
+    char* str = const_cast<char *>(emptyString);
+    uint16_t size_ = 0;   // if size_ == 0 no allocation, but str = emptyString
+    uint8_t free_ = 0;    // malloc(str) = size_ + free_
+
+    static const char* emptyString;
+    const uint8_t extent = 8;
+};
+
+#pragma pack(pop)
diff --git a/tests/Makefile b/tests/Makefile
index 87b61dd..5580c4d 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -1,21 +1,29 @@
+SUB=
+
 tests:
 	@set -e; \
 	for i in $(SUB)*-tests/Makefile; do \
-		$(MAKE) -C $$(dirname $$i) -j clean; \
 		echo '==== Making:' $$(dirname $$i); \
 		$(MAKE) -C $$(dirname $$i) -j; \
 	done
 
+valgrind:
+	@set -e; \
+	$(MAKE) tests; \
+	for i in $(SUB)*-tests/Makefile; do \
+		echo '==== Running:' $$(dirname $$i); \
+		valgrind $$(dirname $$i)/$$(dirname $$i).out; \
+	done
+
 debugtest:
 	@set -e; \
 	$(MAKE) clean; \
 	$(MAKE) -C debug-mode -j; \
 	debug-mode/debug-tests.out
 
-runtests: debugtest
-	@$(MAKE) clean
-	@$(MAKE) tests
+runtests:
 	@set -e; \
+	$(MAKE) tests; \
 	for i in $(SUB)*-tests/Makefile; do \
 		echo '==== Running:' $$(dirname $$i); \
 		$$(dirname $$i)/$$(dirname $$i).out; \
diff --git a/tests/classbind-tests/classbind-tests.ino b/tests/classbind-tests/classbind-tests.ino
index cc53977..bd00c2d 100644
--- a/tests/classbind-tests/classbind-tests.ino
+++ b/tests/classbind-tests/classbind-tests.ino
@@ -340,7 +340,7 @@ void setup() {
   while(!Serial);
   */
 
-  Serial.println("=============[ FAKE NETWORK TinyMqtt TESTS       ]========================");
+  Serial.println("=============[ TinyMqtt class-bind TESTS       ]========================");
 
   WiFi.mode(WIFI_STA);
   WiFi.begin("network", "password");
diff --git a/tests/local-tests/Makefile b/tests/local-tests/Makefile
index e1c23a9..1fe9d48 100644
--- a/tests/local-tests/Makefile
+++ b/tests/local-tests/Makefile
@@ -1,10 +1,7 @@
 # See https://github.com/bxparks/EpoxyDuino for documentation about this
 # Makefile to compile and run Arduino programs natively on Linux or MacOS.
 
-EXTRA_CXXFLAGS=-g3 -O0
-
-# Remove flto flag from EpoxyDuino (too many <optimized out>)
-CXXFLAGS = -Wextra -Wall -std=gnu++11 -fno-exceptions -fno-threadsafe-statics
+include ../Makefile.opts
 
 APP_NAME := local-tests
 ARDUINO_LIBS := AUnit AceCommon AceTime TinyMqtt EspMock ESP8266WiFi  ESPAsyncTCP TinyConsole
diff --git a/tests/local-tests/local-tests.ino b/tests/local-tests/local-tests.ino
index 75305b0..6e5139d 100644
--- a/tests/local-tests/local-tests.ino
+++ b/tests/local-tests/local-tests.ino
@@ -16,7 +16,7 @@ using namespace std;
 
 MqttBroker broker(1883);
 
-std::map<std::string, std::map<Topic, int>>  published;    // map[client_id] => map[topic] = count
+std::map<TinyString, std::map<Topic, int>>  published;    // map[client_id] => map[topic] = count
 
 const char* lastPayload;
 size_t lastLength;
@@ -40,7 +40,7 @@ test(local_client_should_unregister_when_destroyed)
   assertEqual(broker.clientsCount(), (size_t)0);
 }
 
-test(local_client_do_not_disconnect_after_publishing)
+test(local_client_do_not_disconnect_after_publishing_and_long_inactivity)
 {
   EpoxyTest::set_millis(0);
   MqttBroker broker(1883);
@@ -56,11 +56,16 @@ test(local_client_do_not_disconnect_after_publishing)
   sender.publish("test", "value");
   broker.loop();
 
-  EpoxyTest::add_seconds(60);
+  EpoxyTest::add_seconds(600);
   client.loop();
   sender.loop();
   broker.loop();
 
+  sender.publish("test", "value");
+  broker.loop();
+  sender.loop();
+  broker.loop();
+
   assertEqual(broker.clientsCount(), (size_t)2);
   assertEqual(sender.connected(), true);
   assertEqual(client.connected(), true);
diff --git a/tests/network-tests/Makefile b/tests/network-tests/Makefile
index 94f4d89..f3ef323 100644
--- a/tests/network-tests/Makefile
+++ b/tests/network-tests/Makefile
@@ -1,10 +1,10 @@
 # See https://github.com/bxparks/EpoxyDuino for documentation about this
 # Makefile to compile and run Arduino programs natively on Linux or MacOS.
 
-EXTRA_CXXFLAGS=-g3 -O0
+include ../Makefile.opts
 
 # Remove flto flag from EpoxyDuino (too many <optimized out>)
-CXXFLAGS = -Wextra -Wall -std=gnu++11 -fno-exceptions -fno-threadsafe-statics
+# CXXFLAGS = -Wextra -Wall -std=gnu++11 -fno-exceptions -fno-threadsafe-statics
 
 APP_NAME := network-tests
 ARDUINO_LIBS := AUnit AceCommon AceTime TinyMqtt EspMock ESP8266WiFi  ESPAsyncTCP TinyConsole
diff --git a/tests/network-tests/network-tests.ino b/tests/network-tests/network-tests.ino
index b758eda..3e1ca00 100644
--- a/tests/network-tests/network-tests.ino
+++ b/tests/network-tests/network-tests.ino
@@ -78,7 +78,7 @@ String toString(const IPAddress& ip)
 
 MqttBroker broker(1883);
 
-std::map<std::string, std::map<Topic, int>>  published;    // map[client_id] => map[topic] = count
+std::map<TinyString, std::map<Topic, int>>  published;    // map[client_id] => map[topic] = count
 
 char* lastPayload = nullptr;
 size_t lastLength;
@@ -463,4 +463,5 @@ void loop() {
   aunit::TestRunner::run();
 
   if (Serial.available()) ESP.reset();
+  published.clear();  // Avoid crash in unit tests due to exit handlers
 }
diff --git a/tests/nowifi-tests/Makefile b/tests/nowifi-tests/Makefile
index 7a0ccfb..4ad4f03 100644
--- a/tests/nowifi-tests/Makefile
+++ b/tests/nowifi-tests/Makefile
@@ -1,10 +1,7 @@
 # See https://github.com/bxparks/EpoxyDuino for documentation about this
 # Makefile to compile and run Arduino programs natively on Linux or MacOS.
 
-EXTRA_CXXFLAGS=-g3 -O0
-
-# Remove flto flag from EpoxyDuino (too many <optimized out>)
-CXXFLAGS = -Wextra -Wall -std=gnu++11 -fno-exceptions -fno-threadsafe-statics
+include ../Makefile.opts
 
 APP_NAME := nowifi-tests
 ARDUINO_LIBS := AUnit AceCommon AceTime TinyMqtt EspMock ESP8266WiFi  ESPAsyncTCP TinyConsole
diff --git a/tests/nowifi-tests/nowifi-tests.ino b/tests/nowifi-tests/nowifi-tests.ino
index 7bb06e9..bfd2084 100644
--- a/tests/nowifi-tests/nowifi-tests.ino
+++ b/tests/nowifi-tests/nowifi-tests.ino
@@ -15,7 +15,7 @@ using namespace std;
 
 MqttBroker broker(1883);
 
-std::map<std::string, std::map<Topic, int>>  published;    // map[client_id] => map[topic] = count
+std::map<TinyString, std::map<Topic, int>>  published;    // map[client_id] => map[topic] = count
 
 char* lastPayload = nullptr;
 size_t lastLength;
@@ -279,4 +279,5 @@ void loop() {
   aunit::TestRunner::run();
 
   if (Serial.available()) ESP.reset();
+  published.clear();  // Avoid crash at exit handlers
 }
diff --git a/tests/string-indexer-tests/Makefile b/tests/string-indexer-tests/Makefile
index a6c4dc0..a38285f 100644
--- a/tests/string-indexer-tests/Makefile
+++ b/tests/string-indexer-tests/Makefile
@@ -1,7 +1,7 @@
 # See https://github.com/bxparks/EpoxyDuino for documentation about this
 # Makefile to compile and run Arduino programs natively on Linux or MacOS.
 
-EXTRA_CXXFLAGS=-g3 -O0
+include ../Makefile.opts
 
 APP_NAME := string-indexer-tests
 ARDUINO_LIBS := AUnit AceCommon AceTime TinyMqtt EspMock ESP8266WiFi  ESPAsync TinyConsole
diff --git a/tests/string-indexer-tests/string-indexer-tests.ino b/tests/string-indexer-tests/string-indexer-tests.ino
index 5cb02f6..7ae54ec 100644
--- a/tests/string-indexer-tests/string-indexer-tests.ino
+++ b/tests/string-indexer-tests/string-indexer-tests.ino
@@ -84,7 +84,7 @@ test(indexer_indexed_operator_eq)
 
 test(indexer_get_string)
 {
-  std::string sone("one");
+  TinyString sone("one");
   IndexedString one(sone);
 
   assertTrue(sone==one.str());
diff --git a/tests/topic-tests/Makefile b/tests/topic-tests/Makefile
index a15c2e6..0159cf4 100644
--- a/tests/topic-tests/Makefile
+++ b/tests/topic-tests/Makefile
@@ -1,7 +1,7 @@
 # See https://github.com/bxparks/EpoxyDuino for documentation about this
 # Makefile to compile and run Arduino programs natively on Linux or MacOS.
 
-EXTRA_CXXFLAGS=-g3 -O0
+include ../Makefile.opts
 
 APP_NAME := topic-tests
 ARDUINO_LIBS := AUnit AceCommon AceTime TinyMqtt EspMock ESP8266WiFi  ESPAsync TinyConsole