diff --git a/examples/osgdepthpeeling/Utility.cpp b/examples/osgdepthpeeling/Utility.cpp
index c84e7d88f..57baf8a9b 100644
--- a/examples/osgdepthpeeling/Utility.cpp
+++ b/examples/osgdepthpeeling/Utility.cpp
@@ -14,7 +14,7 @@
 #include <osg/Geode>
 #include <osgDB/FileUtils>
 
-bool Utility::readFile(char* fName, std::string& s)
+bool Utility::readFile(const char* fName, std::string& s)
 {
   std::string foundFile = osgDB::findDataFile(fName);
   if (foundFile.empty()) return false;
diff --git a/examples/osgdepthpeeling/Utility.h b/examples/osgdepthpeeling/Utility.h
index e55404ebb..35dd9b788 100644
--- a/examples/osgdepthpeeling/Utility.h
+++ b/examples/osgdepthpeeling/Utility.h
@@ -19,7 +19,7 @@ namespace Utility
 /*!
   Reads a file and returns a string
  */
-bool readFile(char* fName, std::string& s);
+bool readFile(const char* fName, std::string& s);
 
 /*!
   Converts a number to a string