diff --git a/output.cc b/output.cc
index 41cfbf554..00bff1994 100644
--- a/output.cc
+++ b/output.cc
@@ -512,11 +512,11 @@ std::string protect_xml(const std::string s) {
 
 /* This is a helper function to determine the ordering of the script results
    based on their id. */
-static bool scriptid_lessthan(ScriptResult a, ScriptResult b) {
+static bool scriptid_lessthan(const ScriptResult &a, const ScriptResult &b) {
   return strcmp(a.get_id(), b.get_id()) < 0;
 }
 
-static char *formatScriptOutput(ScriptResult sr) {
+static char *formatScriptOutput(const ScriptResult &sr) {
   std::vector<std::string> lines;
 
   std::string c_output;
diff --git a/portlist.cc b/portlist.cc
index fdbb7aa35..31012b055 100644
--- a/portlist.cc
+++ b/portlist.cc
@@ -440,7 +440,7 @@ void PortList::setServiceProbeResults(u16 portno, int protocol,
 
 
 #ifndef NOLUA
-void PortList::addScriptResult(u16 portno, int protocol, ScriptResult& sr) {
+void PortList::addScriptResult(u16 portno, int protocol, const ScriptResult& sr) {
   Port *port;
 
   port = createPort(portno, protocol);
diff --git a/portlist.h b/portlist.h
index 6b7d892b9..76448b6dd 100644
--- a/portlist.h
+++ b/portlist.h
@@ -308,7 +308,7 @@ class PortList {
   void getServiceDeductions(u16 portno, int protocol, struct serviceDeductions *sd) const;
 
 #ifndef NOLUA
-  void addScriptResult(u16 portno, int protocol, ScriptResult& sr);
+  void addScriptResult(u16 portno, int protocol, const ScriptResult& sr);
 #endif
 
   /* Cycles through the 0 or more "ignored" ports which should be