diff --git a/simgear/scene/model/SGReaderWriterXML.cxx b/simgear/scene/model/SGReaderWriterXML.cxx
index 7a3660f6..0f4cdb95 100644
--- a/simgear/scene/model/SGReaderWriterXML.cxx
+++ b/simgear/scene/model/SGReaderWriterXML.cxx
@@ -54,26 +54,27 @@ sgLoad3DModel_internal(const string &path,
                        osg::Node *(*load_panel)(SGPropertyNode *) = 0,
                        SGPropertyNode *overlay = 0);
 
+
+SGReaderWriterXML::SGReaderWriterXML()
+{
+    supportsExtension("xml", "SimGear xml database format");
+}
+
+SGReaderWriterXML::~SGReaderWriterXML()
+{
+}
+
 const char* SGReaderWriterXML::className() const
 {
     return "XML database reader";
 }
 
-bool SGReaderWriterXML::acceptsExtension(const std::string& extension) const
-{
-    return (osgDB::equalCaseInsensitive(extension, "xml"));
-}
-
 osgDB::ReaderWriter::ReadResult
 SGReaderWriterXML::readNode(const std::string& fileName,
                             const osgDB::ReaderWriter::Options* options) const
 {
     // SG_LOG(SG_GENERAL, SG_ALERT, "SGReaderWriterXML::readNode(" << fileName << ")");
 
-    std::string ext = osgDB::getLowerCaseFileExtension(fileName);
-    if (!acceptsExtension(ext))
-        return ReadResult::FILE_NOT_HANDLED;
-
     const SGReaderWriterXMLOptions* xmlOptions
     = dynamic_cast<const SGReaderWriterXMLOptions*>(options);
 
diff --git a/simgear/scene/model/SGReaderWriterXML.hxx b/simgear/scene/model/SGReaderWriterXML.hxx
index 2d92c3ef..afa5925d 100644
--- a/simgear/scene/model/SGReaderWriterXML.hxx
+++ b/simgear/scene/model/SGReaderWriterXML.hxx
@@ -27,9 +27,10 @@ namespace simgear
 class SGReaderWriterXML : public osgDB::ReaderWriter
 {
 public:
-    virtual const char* className() const;
+    SGReaderWriterXML();
+    virtual ~SGReaderWriterXML();
 
-    virtual bool acceptsExtension(const std::string& extension) const;
+    virtual const char* className() const;
 
     virtual ReadResult readNode(const std::string& fileName,
                                 const osgDB::ReaderWriter::Options* options)
diff --git a/simgear/scene/tgdb/ReaderWriterSTG.cxx b/simgear/scene/tgdb/ReaderWriterSTG.cxx
index 8e7fd2a2..57da979b 100644
--- a/simgear/scene/tgdb/ReaderWriterSTG.cxx
+++ b/simgear/scene/tgdb/ReaderWriterSTG.cxx
@@ -33,17 +33,20 @@
 
 using namespace simgear;
 
+ReaderWriterSTG::ReaderWriterSTG()
+{
+    supportsExtension("stg", "SimGear stg database format");
+}
+
+ReaderWriterSTG::~ReaderWriterSTG()
+{
+}
+
 const char* ReaderWriterSTG::className() const
 {
     return "STG Database reader";
 }
 
-bool ReaderWriterSTG::acceptsExtension(const std::string& extension) const
-{
-    return (osgDB::equalCaseInsensitive(extension, "gz")
-            || osgDB::equalCaseInsensitive(extension, "stg"));
-}
-
 //#define SLOW_PAGER 1
 #ifdef SLOW_PAGER
 #include <unistd.h>
@@ -53,22 +56,8 @@ osgDB::ReaderWriter::ReadResult
 ReaderWriterSTG::readNode(const std::string& fileName,
                           const osgDB::ReaderWriter::Options* options) const
 {
-    std::string ext = osgDB::getLowerCaseFileExtension(fileName);
-    if(!acceptsExtension(ext))
-        return ReadResult::FILE_NOT_HANDLED;
-    std::string stgFileName;
-    if (osgDB::equalCaseInsensitive(ext, "gz")) {
-        stgFileName = osgDB::getNameLessExtension(fileName);
-        if (!acceptsExtension(
-                osgDB::getLowerCaseFileExtension(stgFileName))) {
-            return ReadResult::FILE_NOT_HANDLED;
-        }
-    } else {
-        stgFileName = fileName;
-    }
-    osg::Node* result
-        = TileEntry::loadTileByName(osgDB::getNameLessExtension(stgFileName),
-                                      options);
+    std::string tileName = osgDB::getNameLessExtension(fileName);
+    osg::Node* result = TileEntry::loadTileByName(tileName, options);
     // For debugging race conditions
 #ifdef SLOW_PAGER
     sleep(5);
diff --git a/simgear/scene/tgdb/ReaderWriterSTG.hxx b/simgear/scene/tgdb/ReaderWriterSTG.hxx
index 7f53f65a..7c571ccf 100644
--- a/simgear/scene/tgdb/ReaderWriterSTG.hxx
+++ b/simgear/scene/tgdb/ReaderWriterSTG.hxx
@@ -28,9 +28,10 @@ namespace simgear {
 
 class ReaderWriterSTG : public osgDB::ReaderWriter {
 public:
-    virtual const char* className() const;
+    ReaderWriterSTG();
+    virtual ~ReaderWriterSTG();
 
-    virtual bool acceptsExtension(const std::string& extension) const;
+    virtual const char* className() const;
 
     virtual ReadResult readNode(const std::string& fileName,
                                 const osgDB::ReaderWriter::Options* options)
diff --git a/simgear/scene/tgdb/SGReaderWriterBTG.cxx b/simgear/scene/tgdb/SGReaderWriterBTG.cxx
index a93bfcec..1fa3e981 100644
--- a/simgear/scene/tgdb/SGReaderWriterBTG.cxx
+++ b/simgear/scene/tgdb/SGReaderWriterBTG.cxx
@@ -31,31 +31,24 @@ using namespace simgear;
 
 std::string SGReaderWriterBTGOptions::defaultOptions;
 
+SGReaderWriterBTG::SGReaderWriterBTG()
+{
+    supportsExtension("btg", "SimGear btg database format");
+}
+
+SGReaderWriterBTG::~SGReaderWriterBTG()
+{
+}
+
 const char* SGReaderWriterBTG::className() const
 {
     return "BTG Database reader";
 }
 
-bool SGReaderWriterBTG::acceptsExtension(const std::string& extension) const
-{
-    return (osgDB::equalCaseInsensitive(extension, "gz")
-            || osgDB::equalCaseInsensitive(extension, "btg"));
-}
-
 osgDB::ReaderWriter::ReadResult
 SGReaderWriterBTG::readNode(const std::string& fileName,
                             const osgDB::ReaderWriter::Options* options) const
 {
-    std::string ext = osgDB::getLowerCaseFileExtension(fileName);
-    if(!acceptsExtension(ext))
-        return ReadResult::FILE_NOT_HANDLED;
-    if (osgDB::equalCaseInsensitive(ext, "gz")) {
-        std::string btgFileName = osgDB::getNameLessExtension(fileName);
-        if (!acceptsExtension(
-                osgDB::getLowerCaseFileExtension(btgFileName))) {
-            return ReadResult::FILE_NOT_HANDLED;
-        }
-    }
     SGMaterialLib* matlib = 0;
     bool calcLights = false;
     bool useRandomObjects = false;
diff --git a/simgear/scene/tgdb/SGReaderWriterBTG.hxx b/simgear/scene/tgdb/SGReaderWriterBTG.hxx
index 3c0ccc80..ca5f4a73 100644
--- a/simgear/scene/tgdb/SGReaderWriterBTG.hxx
+++ b/simgear/scene/tgdb/SGReaderWriterBTG.hxx
@@ -23,10 +23,11 @@
 
 class SGReaderWriterBTG : public osgDB::ReaderWriter {
 public:
+    SGReaderWriterBTG();
+    virtual ~SGReaderWriterBTG();
+
     virtual const char* className() const;
  
-    virtual bool acceptsExtension(const std::string& extension) const;
-
     virtual ReadResult readNode(const std::string& fileName,
                                 const osgDB::ReaderWriter::Options* options)
         const;