diff --git a/Util/IniFile.h b/Util/IniFile.h
index 0a9c26216..9ca85a3fe 100644
--- a/Util/IniFile.h
+++ b/Util/IniFile.h
@@ -35,7 +35,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 class IniFile {
 public:
-    IniFile(const char * config_filename);
+    explicit IniFile(const char * config_filename);
 
     std::string GetParameter(const std::string & key);
 
diff --git a/Util/OSRMException.h b/Util/OSRMException.h
index 322124435..32597d357 100644
--- a/Util/OSRMException.h
+++ b/Util/OSRMException.h
@@ -33,8 +33,8 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 class OSRMException: public std::exception {
 public:
-    OSRMException(const char * message) : message(message) {}
-    OSRMException(const std::string & message) : message(message) {}
+    explicit OSRMException(const char * message) : message(message) {}
+    explicit OSRMException(const std::string & message) : message(message) {}
     virtual ~OSRMException() throw() {}
 private:
     virtual const char* what() const throw() {