diff --git a/src/cpim/parser/cpim-parser.cpp b/src/cpim/parser/cpim-parser.cpp
index 1235b0896..8d2a88e97 100644
--- a/src/cpim/parser/cpim-parser.cpp
+++ b/src/cpim/parser/cpim-parser.cpp
@@ -355,22 +355,22 @@ bool Cpim::Parser::coreHeaderIsValid<Cpim::DateTimeHeader>(const string &headerV
 		return false;
 
 	// Check date.
-	const int year = stoi(headerValue.substr(0, 4));
+	const int year = Utils::stoi(headerValue.substr(0, 4));
 	const bool isLeapYear = (year % 4 == 0 && year % 100 != 0) || year % 400 == 0;
 
-	const int month = stoi(headerValue.substr(5, 2));
+	const int month = Utils::stoi(headerValue.substr(5, 2));
 	if (month < 1 || month > 12)
 		return false;
 
-	const int day = stoi(headerValue.substr(8, 2));
+	const int day = Utils::stoi(headerValue.substr(8, 2));
 	if (day < 1 || (month == 2 && isLeapYear ? day > 29 : day > daysInMonth[month - 1]))
 		return false;
 
 	// Check time.
 	if (
-		stoi(headerValue.substr(11, 2)) > 24 ||
-		stoi(headerValue.substr(14, 2)) > 59 ||
-		stoi(headerValue.substr(17, 2)) > 60
+		Utils::stoi(headerValue.substr(11, 2)) > 24 ||
+		Utils::stoi(headerValue.substr(14, 2)) > 59 ||
+		Utils::stoi(headerValue.substr(17, 2)) > 60
 	)
 		return false;
 
@@ -378,8 +378,8 @@ bool Cpim::Parser::coreHeaderIsValid<Cpim::DateTimeHeader>(const string &headerV
 	if (headerValue.back() != 'Z') {
 		size_t length = headerValue.length();
 		if (
-			stoi(headerValue.substr(length - 5, 2)) > 24 ||
-			stoi(headerValue.substr(length - 2, 2)) > 59
+			Utils::stoi(headerValue.substr(length - 5, 2)) > 24 ||
+			Utils::stoi(headerValue.substr(length - 2, 2)) > 59
 		)
 			return false;
 	}
diff --git a/src/utils/utils.cpp b/src/utils/utils.cpp
index 9e32a883a..029baaa34 100644
--- a/src/utils/utils.cpp
+++ b/src/utils/utils.cpp
@@ -47,3 +47,13 @@ vector<string> Utils::split (const string &str, const string &delimiter) {
 
 	return out;
 }
+
+int Utils::stoi (const string &str, size_t *idx, int base) {
+	char *p;
+	int v = strtol(str.c_str(), &p, base);
+
+	if (idx)
+		*idx = p - str.c_str();
+
+	return v;
+}
diff --git a/src/utils/utils.h b/src/utils/utils.h
index 1fc468add..d061b9e35 100644
--- a/src/utils/utils.h
+++ b/src/utils/utils.h
@@ -33,6 +33,8 @@ namespace LinphonePrivate {
 		inline std::vector<std::string> split (const std::string &str, char delimiter) {
 			return split(str, std::string(1, delimiter));
 		}
+
+		int stoi (const std::string &str, size_t *idx = 0, int base = 10);
 	}
 }