diff --git a/common/rfb/Configuration.cxx b/common/rfb/Configuration.cxx
index 6811a79..e9eee1a 100644
--- a/common/rfb/Configuration.cxx
+++ b/common/rfb/Configuration.cxx
@@ -418,6 +418,12 @@
   strFree(value);
 }
 
+void StringParameter::setDefaultStr(const char* v) {
+  def_value = v;
+  strFree(value);
+  value = strDup(v);
+}
+
 bool StringParameter::setParam(const char* v) {
   LOCK_CONFIG;
   if (immutable) return true;
diff --git a/common/rfb/Configuration.h b/common/rfb/Configuration.h
index 3e21b18..276651d 100644
--- a/common/rfb/Configuration.h
+++ b/common/rfb/Configuration.h
@@ -240,6 +240,7 @@
     virtual bool setParam(const char* value);
     virtual char* getDefaultStr() const;
     virtual char* getValueStr() const;
+    void setDefaultStr(const char* v);
 
     // getData() returns a copy of the data - it must be delete[]d by the
     // caller.