diff --git a/include/mtl/string.hpp b/include/mtl/string.hpp
index f6cd944..92e2220 100644
--- a/include/mtl/string.hpp
+++ b/include/mtl/string.hpp
@@ -33,6 +33,8 @@ public:
 
 	istring(char* _str, size_t _capacity, size_t _size);
 
+	operator string_view() const { return string_view(m_str, m_size); }
+
 	// Data functions
 	
 	// If the new string does not fit, it will be truncated to the capacity
@@ -112,8 +114,6 @@ public:
 	 *
 	 * Inserting a substring of the destination string is not supported.
 	 */
-	istring& insert(size_t index, const istring& str);
-	istring& insert(size_t index, const istring& str, size_t s_index, size_t count = npos);
 	istring& insert(size_t index, const string_view& str);
 	istring& insert(size_t index, const string_view& str, size_t str_index, size_t count = npos);
 	istring& insert(size_t index, size_t count, char ch);
@@ -130,8 +130,6 @@ public:
 	void push_back(char ch);
 	void pop_back();
 
-	istring& append(const istring& str);
-	istring& append(const istring& str, size_t s_index, size_t count = npos);
 	istring& append(const string_view& str);
 	istring& append(const string_view& str, size_t str_index, size_t count = npos);
 	istring& append(size_t count, char ch);
@@ -141,14 +139,9 @@ public:
 
 	istring& operator+=(char ch);
 	istring& operator+=(const string_view& str);
-	istring& operator+=(const istring& str);
 
-	istring& replace(size_t pos, size_t count, const istring& str);
-	istring& replace(const_iterator first, const_iterator last, const istring& str);
-	istring& replace(size_t pos, size_t count, const istring& str, size_t pos2, size_t count2 = npos);
-	istring& replace(size_t pos, size_t count, const string_view& str, size_t pos2, size_t count2 = npos);
-	istring& replace(const_iterator first, const_iterator last, const string_view& str, size_t pos2, size_t count2 = npos);
 	istring& replace(size_t pos, size_t count, const string_view& str);
+	istring& replace(size_t pos, size_t count, const string_view& str, size_t pos2, size_t count2 = npos);
 	istring& replace(const_iterator first, const_iterator last, const string_view& str);
 	istring& replace(size_t pos, size_t count, size_t count2, char ch);
 	istring& replace(const_iterator first, const_iterator last, size_t count2, char ch);
@@ -169,46 +162,30 @@ public:
 
 	// Search
 	
-	size_t find(const istring& str, size_t pos = 0) const;
 	size_t find(const string_view& str, size_t pos = 0) const;
 	size_t find(char ch, size_t pos = 0) const;
 
-	size_t rfind(const istring& str, size_t pos = npos) const;
 	size_t rfind(const string_view& str, size_t pos = npos) const;
 	size_t rfind(char ch, size_t pos = npos) const;
 
-	size_t find_first_of(const istring& str, size_t pos = 0) const;
 	size_t find_first_of(const string_view& str, size_t pos = 0) const;
 	size_t find_first_of(char ch, size_t pos = 0) const;
 
-	size_t find_first_not_of(const istring& str, size_t pos = 0) const;
 	size_t find_first_not_of(const string_view& str, size_t pos = 0) const;
 	size_t find_first_not_of(char ch, size_t pos = 0) const;
 
-	size_t find_last_of(const istring& str, size_t pos = npos) const;
 	size_t find_last_of(const string_view& str, size_t pos = npos) const;
 	size_t find_last_of(char ch, size_t pos = npos) const;
 
-	size_t find_last_not_of(const istring& str, size_t pos = npos) const;
 	size_t find_last_not_of(const string_view& str, size_t pos = npos) const;
 	size_t find_last_not_of(char ch, size_t pos = npos) const;
 
 	// Comparison
 	
-	int32_t compare(const istring& str) const;
-	int32_t compare(size_t pos, size_t count, const istring& str) const;
-	int32_t compare(size_t pos1, size_t count1, istring& str, size_t pos2, size_t count2 = npos) const;
 	int32_t compare(const string_view& str) const;
 	int32_t compare(size_t pos, size_t count, const string_view& str) const;
 	int32_t compare(size_t pos1, size_t count1, const string_view& str, size_t pos2, size_t count2 = npos) const;
 
-	friend bool operator==(const istring& lhs, const istring& rhs);
-	friend bool operator!=(const istring& lhs, const istring& rhs);
-	friend bool operator<(const istring& lhs, const istring& rhs);
-	friend bool operator<=(const istring& lhs, const istring& rhs);
-	friend bool operator>(const istring& lhs, const istring& rhs);
-	friend bool operator>=(const istring& lhs, const istring& rhs);
-
 	friend bool operator==(const istring& lhs, const string_view& rhs);
 	friend bool operator==(const string_view& lhs, const istring& rhs);
 	friend bool operator!=(const istring& lhs, const string_view& rhs);
@@ -237,6 +214,8 @@ public:
 		mtl::memcpy(m_buf, str.c_str(), m_size);
 		m_str[m_size] = '\0';
 	}
+
+	using istring::operator=;
 };
 
 class string_ext : public istring {
diff --git a/src/string.cpp b/src/string.cpp
index 15c5610..150f350 100644
--- a/src/string.cpp
+++ b/src/string.cpp
@@ -191,7 +191,7 @@ void istring::clear() {
 	m_size = 0;
 }
 
-istring& istring::insert(size_t index, const istring& str) {
+istring& istring::insert(size_t index, const string_view& str) {
 	char* substr = m_str + index;
 
 	size_t space = m_capacity - index;
@@ -213,7 +213,7 @@ istring& istring::insert(size_t index, const istring& str) {
 	return *this;
 }
 
-istring& istring::insert(size_t index, const istring& str, size_t str_index, size_t count) {
+istring& istring::insert(size_t index, const string_view& str, size_t str_index, size_t count) {
 	if (count == npos) {
 		count = str.m_size - str_index;
 	}