diff --git a/teensy/teensy-filemanager.h b/teensy/teensy-filemanager.h
index a98db9d..0367fea 100644
--- a/teensy/teensy-filemanager.h
+++ b/teensy/teensy-filemanager.h
@@ -3,6 +3,7 @@
 
 #include "filemanager.h"
 #include <stdint.h>
+#include <SdFat.h>
 
 class TeensyFileManager : public FileManager {
  public:
@@ -29,9 +30,11 @@ class TeensyFileManager : public FileManager {
   bool _prepCache(int8_t fd);
 
  private:
-  bool enabled;
+  volatile int8_t numCached;
 
-  int8_t numCached;
+  volatile SdFatSdio sd;
+  volatile int8_t cacheFd;
+  volatile FatFile cacheFile;
 };
 
 #endif