diff --git a/src/option_manager.cc b/src/option_manager.cc
index ee329d89..8e55c2eb 100644
--- a/src/option_manager.cc
+++ b/src/option_manager.cc
@@ -5,13 +5,6 @@
 namespace Kakoune
 {
 
-String int_to_str(int value)
-{
-    std::ostringstream oss;
-    oss << value;
-    return oss.str();
-}
-
 Option& OptionManager::operator[] (const String& name)
 {
     auto it = m_options.find(name);
diff --git a/src/string.cc b/src/string.cc
new file mode 100644
index 00000000..30654256
--- /dev/null
+++ b/src/string.cc
@@ -0,0 +1,46 @@
+#include "string.hh"
+
+namespace Kakoune
+{
+
+String int_to_str(int value)
+{
+    const bool negative = value < 0;
+    if (negative)
+        value = -value;
+
+    char buffer[16];
+    size_t pos = sizeof(buffer);
+    buffer[--pos] = 0;
+    do
+    {
+        buffer[--pos] = '0' + (value % 10);
+        value /= 10;
+    }
+    while (value);
+
+    if (negative)
+       buffer[--pos] = '-';
+
+    return String(buffer + pos);
+}
+
+std::vector<String> split(const String& str, Character separator)
+{
+    auto begin = str.begin();
+    auto end   = str.begin();
+
+    std::vector<String> res;
+    while (end != str.end())
+    {
+        while (end != str.end() and *end != separator)
+            ++end;
+        res.push_back(String(begin, end));
+        if (end == str.end())
+            break;
+        begin = ++end;
+    }
+    return res;
+}
+
+}
diff --git a/src/string.hh b/src/string.hh
index d751d9ce..64ee9992 100644
--- a/src/string.hh
+++ b/src/string.hh
@@ -109,6 +109,9 @@ inline String operator+(Character lhs, const String& rhs)
     return String(lhs) + rhs;
 }
 
+String int_to_str(int value);
+std::vector<String> split(const String& str, Character separator);
+
 }
 
 namespace std
diff --git a/src/unit_tests.cc b/src/unit_tests.cc
index 8fee1000..a3bfc427 100644
--- a/src/unit_tests.cc
+++ b/src/unit_tests.cc
@@ -45,8 +45,24 @@ void test_editor()
     }
 }
 
+void test_string()
+{
+   assert(int_to_str(124)  == "124");
+   assert(int_to_str(-129) == "-129");
+   assert(int_to_str(0)    == "0");
+
+   assert(String("youpi ") + "matin" == "youpi matin");
+
+   std::vector<String> splited = split("youpi:matin::tchou", ':');
+   assert(splited[0] == "youpi");
+   assert(splited[1] == "matin");
+   assert(splited[2] == "");
+   assert(splited[3] == "tchou");
+}
+
 void run_unit_tests()
 {
+    test_string();
     test_buffer();
     test_editor();
 }