diff --git a/pdns/qtype.cc b/pdns/qtype.cc
index a0d5732cd10e..710421f97770 100644
--- a/pdns/qtype.cc
+++ b/pdns/qtype.cc
@@ -166,7 +166,23 @@ QType &QType::operator=(const string &s)
   return *this;
 }
 
-const std::string QClass::toString() const
+static const std::map<const std::string, uint16_t> s_classMap = {
+  {"IN", QClass::IN},
+  {"CHAOS", QClass::CHAOS},
+  {"NONE", QClass::NONE},
+  {"ANY", QClass::ANY},
+};
+
+QClass::QClass(const std::string& code)
+{
+  auto mapIt = s_classMap.find(code);
+  if (mapIt == s_classMap.end()) {
+    throw std::runtime_error("Invalid QClass '" + code + "'");
+  }
+  qclass = mapIt->second;
+}
+
+std::string QClass::toString() const
 {
   switch (qclass) {
   case IN:
diff --git a/pdns/qtype.hh b/pdns/qtype.hh
index f5a879bef8f5..dd2761a65f29 100644
--- a/pdns/qtype.hh
+++ b/pdns/qtype.hh
@@ -178,6 +178,7 @@ inline size_t hash_value(const QType qtype) {
 struct QClass
 {
   constexpr QClass(uint16_t code = 0) : qclass(code) {}
+  explicit QClass(const std::string& code);
 
   constexpr operator uint16_t() const {
     return qclass;
@@ -186,7 +187,7 @@ struct QClass
   {
     return qclass;
   }
-  const std::string toString() const;
+  std::string toString() const;
 
   static const QClass IN;
   static const QClass CHAOS;