diff --git a/auxstorage.h b/auxstorage.h
index 8d860df..c8d668c 100644
--- a/auxstorage.h
+++ b/auxstorage.h
@@ -11,16 +11,20 @@
 #include <fcntl.h>
 #include <unistd.h>
 
+//CAUTION:
+//it will not work if T is itself a class with dynamically allocated components
+//it cannot be implemented for SparseMat, which lacks fixed record length
+
 
 template<typename T>
 class AuxStorage
 	{
-	char filename[16];
+	char filename[32];
 	int fd;
-	off64_t recl;
+	size_t recl;
 public:
 	AuxStorage(void);
-	~AuxStorage(void) {close(fd);};
+	~AuxStorage(void) {close(fd); unlink(filename);};
 	void get(NRVec<T> &x, const int pos) const;
 	void put(const NRVec<T> &x, const int pos);
         void get(NRMat<T> &x, const int pos) const;
@@ -32,10 +36,10 @@ public:
 template<typename T>
 AuxStorage<T>::AuxStorage(void)
 {
-strcpy(filename,"AuxStorageXXXXXX"); 
+strcpy(filename,"AUX_XXXXXX"); 
 mktemp(filename); 
 unlink(filename);
-fd=open(filename,O_CREAT|O_LARGEFILE);
+fd=open(filename,O_CREAT|O_LARGEFILE|O_RDWR,0777);
 if(fd<0) {perror(""); laerror("open failed in AuxStorage");}
 recl=0;
 }
@@ -44,16 +48,16 @@ template<typename T>
 void AuxStorage<T>::get(NRVec<T> &x, const int pos) const
 {
 if(recl==0) laerror("get from an empty file in AuxStorage");
-if((off64_t)-1 == lseek64(fd,pos*recl,SEEK_SET)) {perror(""); laerror("seek failed in AuxStorage");}
-if(recl!=read(fd,&x[0],recl)) {perror(""); laerror("read failed in AuxStorage");}
+if((off64_t)-1 == lseek64(fd,pos*((off64_t)recl),SEEK_SET)) {perror(""); laerror("seek failed in AuxStorage");}
+if((ssize_t)recl!=read(fd,&x[0],recl)) {perror(""); laerror("read failed in AuxStorage");}
 }
 
 template<typename T>
-void AuxStorage<T>::put(const NRVec<T> &x, const int pos) const
+void AuxStorage<T>::put(const NRVec<T> &x, const int pos)
 {
 if(recl) {if(recl!=x.size()*sizeof(T)) laerror("attempt to write objects of different size to one AuxStorage");}
 else recl=x.size()*sizeof(T);
-if((off64_t)-1 == lseek64(fd,pos*recl,SEEK_SET)) {perror(""); laerror("seek failed in AuxStorage");}
+if((off64_t)-1 == lseek64(fd,pos*((off64_t)recl),SEEK_SET)) {perror(""); laerror("seek failed in AuxStorage");}
 if(0>write(fd,&x[0],recl)) {perror(""); laerror("write failed in AuxStorage");}
 }