diff --git a/src/settings.cpp b/src/settings.cpp
index 0576af3883..d238ec97cb 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -578,7 +578,7 @@ void StringSettingDesc::MakeValueValid(std::string &str) const
 	/* In case a maximum length is imposed by the setting, the length
 	 * includes the '\0' termination for network transfer purposes.
 	 * Also ensure the string is valid after chopping of some bytes. */
-	std::string stdstr(str, this->max_length - 1);
+	std::string stdstr(str, 0, this->max_length - 1);
 	str.assign(StrMakeValid(stdstr, SVS_NONE));
 }