diff --git a/src/common/Utilities/Util.h b/src/common/Utilities/Util.h
index 3648c850d..f00c06930 100644
--- a/src/common/Utilities/Util.h
+++ b/src/common/Utilities/Util.h
@@ -351,6 +351,7 @@ inline wchar_t wcharToLower(wchar_t wchar)
 
 void wstrToUpper(std::wstring& str);
 void wstrToLower(std::wstring& str);
+void strToLower(std::string& str);
 
 std::wstring GetMainPartOfName(std::wstring const& wname, uint32 declension);