diff --git a/binding-mri/binding-mri.cpp b/binding-mri/binding-mri.cpp
index 5cb518e..c28cdaa 100644
--- a/binding-mri/binding-mri.cpp
+++ b/binding-mri/binding-mri.cpp
@@ -452,8 +452,9 @@ static void runRMXPScripts(BacktraceData &btData)
 	}
 
 	/* Execute preloaded scripts */
-	for (size_t i = 0; i < conf.preloadScripts.size(); ++i)
-		runCustomScript(conf.preloadScripts[i]);
+	for (std::set<std::string>::iterator i = conf.preloadScripts.begin();
+	     i != conf.preloadScripts.end(); ++i)
+		runCustomScript(*i);
 
 	VALUE exc = rb_gv_get("$!");
 	if (exc != Qnil)
diff --git a/src/config.cpp b/src/config.cpp
index 9173acc..a58ddab 100644
--- a/src/config.cpp
+++ b/src/config.cpp
@@ -134,6 +134,12 @@ static std::string prefPath(const char *org, const char *app)
 	return str;
 }
 
+template<typename T>
+std::set<T> setFromVec(const std::vector<T> &vec)
+{
+	return std::set<T>(vec.begin(), vec.end());
+}
+
 typedef std::vector<std::string> StringVec;
 namespace po = boost::program_options;
 
@@ -226,7 +232,7 @@ void Config::read(int argc, char *argv[])
 
 	PO_DESC_ALL;
 
-	GUARD_ALL( preloadScripts = vm["preloadScript"].as<StringVec>(); );
+	GUARD_ALL( preloadScripts = setFromVec(vm["preloadScript"].as<StringVec>()); );
 
 	GUARD_ALL( rtps = vm["RTP"].as<StringVec>(); );
 
diff --git a/src/config.h b/src/config.h
index fc9bbda..d82698d 100644
--- a/src/config.h
+++ b/src/config.h
@@ -24,6 +24,7 @@
 
 #include <string>
 #include <vector>
+#include <set>
 
 struct Config
 {
@@ -77,7 +78,7 @@ struct Config
 	bool useScriptNames;
 
 	std::string customScript;
-	std::vector<std::string> preloadScripts;
+	std::set<std::string> preloadScripts;
 	std::vector<std::string> rtps;
 
 	std::vector<std::string> fontSubs;