diff --git a/src_main/system/piprocess.h b/src_main/system/piprocess.h
index 57c19382..82c22a08 100755
--- a/src_main/system/piprocess.h
+++ b/src_main/system/piprocess.h
@@ -38,7 +38,7 @@
 /// bool exec(const PIString & program, const PIStringList & args)
 /// void terminate()
 /// bool waitForFinish(int timeout_msecs = 60000)
-class PIP_EXPORT PIProcess: protected PIThread
+class PIP_EXPORT PIProcess: public PIThread
 {
 	PIOBJECT_SUBCLASS(PIProcess, PIThread)
 public:
@@ -70,7 +70,7 @@ public:
 
 	EVENT_HANDLER1(void, exec, const PIString & , program) {args.clear(); args << program; exec_();}
 	void exec(const PIString & program, const PIString & arg) {args.clear(); args << program << arg; exec_();}
-	EVENT_HANDLER2(void, exec, const PIString & , program, const PIStringList & , args_) {args << program << args_; exec_();}
+	EVENT_HANDLER2(void, exec, const PIString & , program, const PIStringList & , args_) {args.clear(); args << program << args_; exec_();}
 	EVENT_HANDLER(void, terminate);
 	EVENT_HANDLER(bool, waitForFinish) {return waitForFinish(60000);}
 	EVENT_HANDLER1(bool, waitForFinish, int, timeout_msecs) {return PIThread::waitForFinish(timeout_msecs);}