diff --git a/include/osgDB/ObjectCache b/include/osgDB/ObjectCache

index 01b3f05..0d8b5be 100644

--- a/include/osgDB/ObjectCache

+++ b/include/osgDB/ObjectCache

@@ -72,7 +72,7 @@ class OSGDB_EXPORT ObjectCache : public osg::Referenced

         class ClassComp {

         public:

-            bool operator() (const ObjectCache::FileNameOptionsPair& lhs, const ObjectCache::FileNameOptionsPair& rhs);

+            bool operator() (const ObjectCache::FileNameOptionsPair& lhs, const ObjectCache::FileNameOptionsPair& rhs) const;

         };

         typedef std::pair<osg::ref_ptr<osg::Object>, double >           ObjectTimeStampPair;

diff --git a/src/osgDB/ObjectCache.cpp b/src/osgDB/ObjectCache.cpp

index 11ca07c..740aa2e 100644

--- a/src/osgDB/ObjectCache.cpp

+++ b/src/osgDB/ObjectCache.cpp

@@ -16,7 +16,7 @@

 using namespace osgDB;

-bool ObjectCache::ClassComp::operator() (const ObjectCache::FileNameOptionsPair& lhs, const ObjectCache::FileNameOptionsPair& rhs)

+bool ObjectCache::ClassComp::operator() (const ObjectCache::FileNameOptionsPair& lhs, const ObjectCache::FileNameOptionsPair& rhs) const

 {

     // check if filename are the same

     if (lhs.first < rhs.first) return true;

	"${FILESDIR}"/openscenegraph-3.4-gcc11.patch