diff --git a/etk-core/String.cpp b/etk-core/String.cpp
index 00fa179..0efe71c 100644
--- a/etk-core/String.cpp
+++ b/etk-core/String.cpp
@@ -25,7 +25,7 @@ etk::String::String():
 		//printf("size of string=%ld   %ld   %ld\n", uint64_t(sizeof(etk::String)), m_sizeLocal, uint64_t(sizeof(etk::Vector<char>)));
 		memset(m_localData, 0, sizeof(m_localData));
 	#else
-		//m_data.resize(1, '\0');
+		m_data.resize(1, '\0');
 	#endif
 }
 
@@ -401,6 +401,7 @@ const etk::String::Iterator etk::String::end() const {
 void etk::String::resize(size_t _newSize, char _value) {
 	if (_newSize == 0) {
 		m_data.clear();
+		m_data.resize(1, '\0');
 		return;
 	}
 	size_t oldSize = m_data.size();
diff --git a/etk-core/String.hpp b/etk-core/String.hpp
index a9e69c5..6f19e48 100644
--- a/etk-core/String.hpp
+++ b/etk-core/String.hpp
@@ -23,15 +23,13 @@ namespace etk {
 		public:
 			class Iterator {
 				private:
-					size_t m_current; //!< current Id on the string
-					String* m_string; //!< Pointer on the current element of the string
+					size_t m_current = 0; //!< current Id on the string
+					String* m_string = null; //!< Pointer on the current element of the string
 				public:
 					/**
 					 * @brief Basic iterator constructor with no link with an etk::String
 					 */
-					Iterator():
-					  m_current(0),
-					  m_string(null) {
+					Iterator() {
 						// nothing to do ...
 					}
 					/**
diff --git a/etk-core/UString.cpp b/etk-core/UString.cpp
index 0939d37..c05e756 100644
--- a/etk-core/UString.cpp
+++ b/etk-core/UString.cpp
@@ -312,14 +312,19 @@ const etk::UString::Iterator etk::UString::begin() const {
 }
 
 etk::UString::Iterator etk::UString::end() {
-	return position( size()-1 );
+	return position( size() );
 }
 
 const etk::UString::Iterator etk::UString::end() const {
-	return position( size()-1 );
+	return position( size() );
 }
 
 void etk::UString::resize(size_t _newSize, char32_t _value) {
+	if (_newSize == 0) {
+		m_data.clear();
+		m_data.resize(1, '\0');
+		return;
+	}
 	size_t oldSize = m_data.size();
 	if (oldSize != 0) {
 		m_data[m_data.size()-1] = _value;
diff --git a/etk-core/UString.hpp b/etk-core/UString.hpp
index 8a45218..1988a7e 100644
--- a/etk-core/UString.hpp
+++ b/etk-core/UString.hpp
@@ -19,15 +19,13 @@ namespace etk {
 		public:
 			class Iterator {
 				private:
-					size_t m_current; //!< current Id on the string
-					UString* m_string; //!< Pointer on the current element of the stringBin
+					size_t m_current = 0; //!< current Id on the string
+					UString* m_string = null; //!< Pointer on the current element of the stringBin
 				public:
 					/**
 					 * @brief Basic iterator constructor with no link with an etk::UString
 					 */
-					Iterator():
-					  m_current(0),
-					  m_string(null) {
+					Iterator() {
 						// nothing to do ...
 					}
 					/**