diff --git a/Audio_File.C b/Audio_File.C
index ac7a60b..18bc6a3 100644
--- a/Audio_File.C
+++ b/Audio_File.C
@@ -20,6 +20,8 @@
 #include "Audio_File.H"
 #include "Audio_File_SF.H"
 
+map <string, Audio_File*> Audio_File::_open_files;
+
 /** attmpet to open any supported filetype */
 Audio_File *
 Audio_File::from_file ( const char * filename )
@@ -27,6 +29,9 @@ Audio_File::from_file ( const char * filename )
 
     Audio_File *a;
 
+    if ( ( a = _open_files[ string( filename ) ] ) )
+        return a;
+
     if ( ( a = Audio_File_SF::from_file( filename ) ) )
         goto done;
 
@@ -36,6 +41,7 @@ Audio_File::from_file ( const char * filename )
 
 done:
 
+
     a->_peaks = new Peaks[ a->channels() ];
 
     for ( int i = a->channels(); i-- ; )
@@ -45,5 +51,7 @@ done:
         a->_peaks[i].open();
     }
 
+    _open_files[ string( filename ) ] = a;
+
     return a;
 }
diff --git a/Audio_File.H b/Audio_File.H
index 19659fc..5aee6ca 100644
--- a/Audio_File.H
+++ b/Audio_File.H
@@ -27,8 +27,13 @@ typedef float sample_t;
 
 #include "Peaks.H"
 
+#include <string>
+#include <map>
+using namespace std;
+
 class Audio_File
 {
+    static map <string, Audio_File*> _open_files;
 
 protected:
 
diff --git a/Audio_File_SF.C b/Audio_File_SF.C
index caf8b5c..30dfb9e 100644
--- a/Audio_File_SF.C
+++ b/Audio_File_SF.C
@@ -41,12 +41,6 @@ Audio_File_SF::from_file ( const char *filename )
         return NULL;
     }
 
-/*     if ( si.channels != 1 ) */
-/*     { */
-/*         printf( "error: incompatible format\n" ); */
-/*         goto invalid; */
-/*     } */
-
     if ( si.samplerate != timeline->sample_rate )
     {
         printf( "error: samplerate mismatch!\n" );
@@ -55,7 +49,7 @@ Audio_File_SF::from_file ( const char *filename )
 
     c = new Audio_File_SF;
 
-    c->_filename = filename;
+    c->_filename = strdup( filename );
     c->_length = si.frames;
     c->_channels = si.channels;