diff --git a/lib/Core/Plot.cpp b/lib/Core/Plot.cpp
index 7c87a52..0cde425 100644
--- a/lib/Core/Plot.cpp
+++ b/lib/Core/Plot.cpp
@@ -580,7 +580,7 @@ Plot & Plot::operator<<(PlotModifier &&modifier)
 }
 
 // find gnuplot ////////////////////////////////////////////////////////////////
-void Plot::getProgramPath(void)
+std::string Plot::getProgramPath(void)
 {
     int         i, j, lg;
     char        *path;
@@ -640,6 +640,8 @@ void Plot::getProgramPath(void)
         buf[lg] = 0;
         gnuplotPath_ = buf;
     }
+
+    return gnuplotPath_;
 }
 
 // plot parsing and output /////////////////////////////////////////////////////
diff --git a/lib/Core/Plot.hpp b/lib/Core/Plot.hpp
index bbc1c47..024bca2 100644
--- a/lib/Core/Plot.hpp
+++ b/lib/Core/Plot.hpp
@@ -381,9 +381,9 @@ public:
     friend std::ostream & operator<<(std::ostream &out, const Plot &plot);
     // plot reset
     void reset(void);
-private:
     // find gnuplot
-    void getProgramPath(void);
+    std::string getProgramPath(void);
+private:
     // default options
     void initOptions(void);
 private: