diff --git a/CHANGES b/CHANGES
index 94766a5..89fd9fc 100644
--- a/CHANGES
+++ b/CHANGES
@@ -6,6 +6,7 @@
     ' '; needed for web servers, so they can serve libstdc++.tar.gz)
   fix iob_write to handle failure properly
   document that the iob_write callback should limit itself
+  add iob_free, add man pages for iob_free and iob_reset
 
 0.21:
   errno cleanup and man page updates (Rolf Eike Beer)
diff --git a/buffer/buffer_close.c b/buffer/buffer_close.c
index 6d8127a..41d57d9 100644
--- a/buffer/buffer_close.c
+++ b/buffer/buffer_close.c
@@ -1,13 +1,22 @@
 #include <buffer.h>
 #include <stdlib.h>
 #include <unistd.h>
+#ifdef __MINGW32__
+#include <windows.h>
+#else
 #include <sys/mman.h>
+#endif
 
 void buffer_close(buffer* b) {
   if (b->fd != -1) close(b->fd);
   switch (b->todo) {
   case FREE: free(b->x); break;
-  case MUNMAP: munmap(b->x,b->a); break;
+  case MUNMAP:
+#ifdef __MINGW32__
+    UnmapViewOfFile(b->x);
+#else
+    munmap(b->x,b->a); break;
+#endif
   default: ;
   }
 }
diff --git a/buffer/errmsg_cvt.c b/buffer/errmsg_cvt.c
index e80ce1e..be350cf 100644
--- a/buffer/errmsg_cvt.c
+++ b/buffer/errmsg_cvt.c
@@ -1,6 +1,15 @@
 #include <stdarg.h>
 #include <sys/types.h>
+#ifdef __MINGW32__
+#include "windows.h"
+
+struct iovec {
+  LPCVOID iov_base;
+  DWORD iov_len;
+};
+#else
 #include <sys/uio.h>
+#endif
 #include "errmsg.h"
 #include "str.h"
 
diff --git a/buffer/errmsg_info.c b/buffer/errmsg_info.c
index fd39da7..b2a4c8e 100644
--- a/buffer/errmsg_info.c
+++ b/buffer/errmsg_info.c
@@ -1,6 +1,16 @@
 #include <stdarg.h>
 #include <sys/types.h>
+#ifdef __MINGW32__
+#include "windows.h"
+#include <unistd.h>
+
+struct iovec {
+  LPCVOID iov_base;
+  DWORD iov_len;
+};
+#else
 #include <sys/uio.h>
+#endif
 #include "errmsg.h"
 #include "str.h"
 
@@ -10,6 +20,15 @@ void errmsg_info(const char* message, ...) {
   struct iovec x[23];
   va_list a;
   va_start(a,message);
+#ifdef __MINGW32__
+  {
+    int i,j;
+    j=errmsg_cvt(x,message,a);
+    for (i=0; i<j; ++i)
+      write(1,x[i].iov_base,x[i].iov_len);
+  }
+#else
   writev(1,x,errmsg_cvt(x,message,a));
+#endif
   va_end(a);
 }
diff --git a/buffer/errmsg_infosys.c b/buffer/errmsg_infosys.c
index b239123..e27a9ec 100644
--- a/buffer/errmsg_infosys.c
+++ b/buffer/errmsg_infosys.c
@@ -1,12 +1,10 @@
 #include <stdarg.h>
 #include <sys/types.h>
-#include <sys/uio.h>
 #include "errmsg.h"
 #include "str.h"
 #include <string.h>
 #include <errno.h>
 
-extern int errmsg_cvt(struct iovec* x,const char* message, va_list a);
 extern void errmsg_writesys(int fd,const char* message,va_list list);
 
 void errmsg_infosys(const char* message, ...) {
diff --git a/buffer/errmsg_warn.c b/buffer/errmsg_warn.c
index 013c531..5fc7ce5 100644
--- a/buffer/errmsg_warn.c
+++ b/buffer/errmsg_warn.c
@@ -1,6 +1,16 @@
 #include <stdarg.h>
 #include <sys/types.h>
+#ifdef __MINGW32__
+#include "windows.h"
+#include <unistd.h>
+
+struct iovec {
+  LPCVOID iov_base;
+  DWORD iov_len;
+};
+#else
 #include <sys/uio.h>
+#endif
 #include "errmsg.h"
 #include "str.h"
 
@@ -10,6 +20,15 @@ void errmsg_warn(const char* message, ...) {
   struct iovec x[23];
   va_list a;
   va_start(a,message);
+#ifdef __MINGW32__
+  {
+    int i,j;
+    j=errmsg_cvt(x,message,a);
+    for (i=0; i<j; ++i)
+      write(2,x[i].iov_base,x[i].iov_len);
+  }
+#else
   writev(2,x,errmsg_cvt(x,message,a));
+#endif
   va_end(a);
 }
diff --git a/buffer/errmsg_warnsys.c b/buffer/errmsg_warnsys.c
index 7e10c21..7823381 100644
--- a/buffer/errmsg_warnsys.c
+++ b/buffer/errmsg_warnsys.c
@@ -1,12 +1,10 @@
 #include <stdarg.h>
 #include <sys/types.h>
-#include <sys/uio.h>
 #include "errmsg.h"
 #include "str.h"
 #include <string.h>
 #include <errno.h>
 
-extern int errmsg_cvt(struct iovec* x,const char* message, va_list a);
 extern void errmsg_writesys(int fd,const char* message,va_list list);
 
 void errmsg_warnsys(const char* message, ...) {
diff --git a/buffer/errmsg_writesys.c b/buffer/errmsg_writesys.c
index 1fb93e4..82f8713 100644
--- a/buffer/errmsg_writesys.c
+++ b/buffer/errmsg_writesys.c
@@ -1,6 +1,16 @@
 #include <stdarg.h>
 #include <sys/types.h>
+#ifdef __MINGW32__
+#include "windows.h"
+#include <unistd.h>
+
+struct iovec {
+  LPCVOID iov_base;
+  DWORD iov_len;
+};
+#else
 #include <sys/uio.h>
+#endif
 #include "errmsg.h"
 #include "str.h"
 #include <string.h>
@@ -22,5 +32,13 @@ void errmsg_writesys(int fd,const char* message,va_list list) {
   x[i+1].iov_base="\n";
   x[i+1].iov_len=1;
 
+#ifdef __MINGW32__
+  {
+    int j;
+    for (j=0; j<i+2; ++j)
+      write(2,x[j].iov_base,x[j].iov_len);
+  }
+#else
   writev(2,x,i+2);
+#endif
 }
diff --git a/io/io_close.c b/io/io_close.c
index 097c153..c7bd7b0 100644
--- a/io/io_close.c
+++ b/io/io_close.c
@@ -1,6 +1,10 @@
 #include <unistd.h>
 #include <sys/types.h>
+#ifdef __MINGW32__
+#include <windows.h>
+#else
 #include <sys/mman.h>
+#endif
 #include "io_internal.h"
 
 void io_close(int64 d) {
@@ -10,7 +14,12 @@ void io_close(int64 d) {
     io_dontwantread(d);
     io_dontwantwrite(d);
     if (e->mmapped) {
+#ifdef __MINGW32__
+      UnmapViewOfFile(e->mmapped);
+      CloseHandle(e->mh);
+#else
       munmap(e->mmapped,e->maplen);
+#endif
       e->mmapped=0;
     }
   }
diff --git a/io/io_fd.c b/io/io_fd.c
index 410002b..b707c40 100644
--- a/io/io_fd.c
+++ b/io/io_fd.c
@@ -54,7 +54,9 @@ int io_fd(int64 d) {
   if (!(e=array_allocate(&io_fds,sizeof(io_entry),d))) return 0;
   byte_zero(e,sizeof(io_entry));
   e->inuse=1;
-#ifndef __MINGW32__
+#ifdef __MINGW32__
+  e->mh=0;
+#else
   if (r&O_NDELAY) e->nonblock=1;
 #endif
   e->next_read=e->next_write=-1;
diff --git a/io/io_mmapwritefile.c b/io/io_mmapwritefile.c
index 9b0d62a..8866fc4 100644
--- a/io/io_mmapwritefile.c
+++ b/io/io_mmapwritefile.c
@@ -2,7 +2,11 @@
 #include <iob.h>
 #include <unistd.h>
 #include <sys/types.h>
+#ifdef __MINGW32__
+#include <windows.h>
+#else
 #include <sys/mman.h>
+#endif
 
 #define BUFSIZE 16384
 
@@ -14,19 +18,33 @@ int64 io_mmapwritefile(int64 out,int64 in,uint64 off,uint64 bytes,io_write_callb
   if (e) {
     const char* c;
     long left;
+#ifdef __MINGW32__
+    if (!e->mh) e->mh=CreateFileMapping(out,0,PAGE_READONLY,0,0,NULL);
+    if (!e->mh) goto readwrite;
+#endif
     do {
       if (e->mmapped) {
 	/* did we already map the right chunk? */
 	if (off>=e->mapofs && off<e->mapofs+e->maplen)
 	  goto mapok;	/* ok; mmapped the right chunk*/
+#ifdef __MINGW32__
+	UnmapViewOfFile(e->mmapped);
+#else
 	munmap(e->mmapped,e->maplen);
+#endif
       }
       e->mapofs=off&0xffffffffffff0000ull;
       if (e->mapofs+0x10000>off+bytes)
 	e->maplen=off+bytes-e->mapofs;
       else
 	e->maplen=0x10000;
-      if ((e->mmapped=mmap(0,e->maplen,PROT_READ,MAP_SHARED,in,e->mapofs))==MAP_FAILED) {
+#ifdef __MINGW32__
+      if ((e->mmapped=MapViewOfFile(e->mh,FILE_MAP_READ,(DWORD)(e->mapofs>>32),
+				    (DWORD)e->mapofs,e->maplen))==0)
+#else
+      if ((e->mmapped=mmap(0,e->maplen,PROT_READ,MAP_SHARED,in,e->mapofs))==MAP_FAILED)
+#endif
+      {
 	e->mmapped=0;
 	goto readwrite;
       }
@@ -40,7 +58,11 @@ int64 io_mmapwritefile(int64 out,int64 in,uint64 off,uint64 bytes,io_write_callb
 	  e->canwrite=0;
 	  e->next_write=-1;
 	  if (errno!=EAGAIN) {
+#ifdef __MINGW32__
+	    UnmapViewOfFile(e->mmapped);
+#else
 	    munmap(e->mmapped,e->maplen);
+#endif
 	    e->mmapped=0;
 	    return -3;
 	  }
@@ -55,7 +77,11 @@ int64 io_mmapwritefile(int64 out,int64 in,uint64 off,uint64 bytes,io_write_callb
       }
     } while (bytes);
     if (e->mmapped) {
+#ifdef __MINGW32__
+      UnmapViewOfFile(e->mmapped);
+#else
       munmap(e->mmapped,e->maplen);
+#endif
       e->mmapped=0;
     }
     return sent;
diff --git a/io/io_passfd.c b/io/io_passfd.c
index f6b371a..8d66081 100644
--- a/io/io_passfd.c
+++ b/io/io_passfd.c
@@ -1,3 +1,12 @@
+#ifdef __MINGW32__
+#include "io_internal.h"
+#include <errno.h>
+int io_passfd(int64 sock,int64 fd) {
+  errno=EINVAL;
+  return -1;
+}
+#else
+
 #include <stddef.h>
 #include <sys/types.h>
 #include <sys/socket.h>
@@ -40,3 +49,4 @@ int io_passfd(int64 sock,int64 fd) {
 #endif
   return sendmsg(sock,&msg,0)>=0?0:-1;
 }
+#endif
diff --git a/io/io_receivefd.c b/io/io_receivefd.c
index 9e8d8a6..dcc1605 100644
--- a/io/io_receivefd.c
+++ b/io/io_receivefd.c
@@ -1,3 +1,12 @@
+#ifdef __MINGW32__
+#include <errno.h>
+#include "io_internal.h"
+int64 io_receivefd(int64 sock) {
+  errno=EINVAL;
+  return -1;
+}
+#else
+
 #include <stddef.h>
 #include <sys/types.h>
 #include <sys/socket.h>
@@ -60,3 +69,4 @@ int64 io_receivefd(int64 sock) {
   return fd;
 #endif
 }
+#endif
diff --git a/io/io_sigpipe.c b/io/io_sigpipe.c
index e92c876..bb800dc 100644
--- a/io/io_sigpipe.c
+++ b/io/io_sigpipe.c
@@ -5,9 +5,11 @@
 /* this is an internal function, called by io_trywrite and io_waitwrite */
 
 void io_sigpipe(void) {
+#ifndef __MINGW32__
   static int isitdone;
   if (!isitdone) {
     signal(SIGPIPE,SIG_IGN);
     isitdone=1;
   }
+#endif
 }
diff --git a/io/io_socketpair.c b/io/io_socketpair.c
index 561213d..b10f435 100644
--- a/io/io_socketpair.c
+++ b/io/io_socketpair.c
@@ -1,12 +1,16 @@
 #include <sys/types.h>
 #include <unistd.h>
+#ifndef __MINGW32__
 #include <sys/socket.h>
 #include <netinet/in.h>
+#endif
+#include "windoze.h"
 #include <errno.h>
 #include "io_internal.h"
 
 int io_socketpair(int64* d) {
   int fds[2];
+  __winsock_init();
   if (socketpair(AF_UNIX,SOCK_STREAM,0,fds)==-1)
     if (socketpair(AF_INET6,SOCK_STREAM,IPPROTO_TCP,fds)==-1)
       if (socketpair(AF_INET,SOCK_STREAM,IPPROTO_TCP,fds)==-1)
diff --git a/io/iob_free.3 b/io/iob_free.3
new file mode 100644
index 0000000..381be95
--- /dev/null
+++ b/io/iob_free.3
@@ -0,0 +1,13 @@
+.TH iob_free 3
+.SH NAME
+iob_free \- free an I/O batch
+.SH SYNTAX
+.B #include <iob.h>
+
+void \fBiob_free\fP(io_batch* b);
+.SH DESCRIPTION
+iob_free frees all resources associated with \fIb\fR.  Calling iob_free
+is equivalent to calling iob_reset and free.
+avoiding unnecessary copying (using writev).
+.SH "SEE ALSO"
+iob_new(3), iob_reset(3)
diff --git a/io/iob_free.c b/io/iob_free.c
new file mode 100644
index 0000000..39bcfa0
--- /dev/null
+++ b/io/iob_free.c
@@ -0,0 +1,7 @@
+#include <stdlib.h>
+#include "iob_internal.h"
+
+void iob_free(io_batch* b) {
+  iob_reset(b);
+  free(b);
+}
diff --git a/io/iob_reset.3 b/io/iob_reset.3
new file mode 100644
index 0000000..81d6658
--- /dev/null
+++ b/io/iob_reset.3
@@ -0,0 +1,16 @@
+.TH iob_reset 3
+.SH NAME
+iob_reset \- reset an I/O batch
+.SH SYNTAX
+.B #include <iob.h>
+
+void \fBiob_reset\fP(io_batch* b);
+.SH DESCRIPTION
+iob_free empties the list of transactions in an I/O batch.  Files added
+with iob_addfile_close are closed, and buffer added with iob_addbuf_free
+of iob_adds_free are freed.
+
+The I/O batch itself is not freed.  You can start adding transactions to
+it again.
+.SH "SEE ALSO"
+iob_new(3), iob_reset(3)
diff --git a/io_internal.h b/io_internal.h
index abf607f..8b67dd7 100644
--- a/io_internal.h
+++ b/io_internal.h
@@ -30,7 +30,7 @@ typedef struct {
   uint64 mapofs;
 #ifdef __MINGW32__
   OVERLAPPED o;
-  HANDLE fd;
+  HANDLE /* fd, */ mh;
 #endif
 } io_entry;
 
diff --git a/iob.h b/iob.h
index 9d9565c..c791ca4 100644
--- a/iob.h
+++ b/iob.h
@@ -31,6 +31,7 @@ int iob_addfile_close(io_batch* b,int64 fd,uint64 off,uint64 n);
 int64 iob_send(int64 s,io_batch* b);
 int64 iob_write(int64 s,io_batch* b,io_write_callback cb);
 void iob_reset(io_batch* b);
+void iob_free(io_batch* b);
 void iob_prefetch(io_batch* b,uint64 bytes);
 
 #endif
diff --git a/test/b64encode.c b/test/b64encode.c
index b1c1a15..95e9ed3 100644
--- a/test/b64encode.c
+++ b/test/b64encode.c
@@ -4,9 +4,9 @@
 #include "textcode.h"
 #include "havealloca.h"
 
-void b64encode(const char* c) {
-  char* buf=alloca(strlen(c)*2+4);
-  buffer_put(buffer_1,buf,fmt_base64(buf,c,strlen(c)));
+void b64encode(const char* c,long len) {
+  char* buf=alloca(len*2+4);
+  buffer_put(buffer_1,buf,fmt_base64(buf,c,len));
   if (isatty(1))
     buffer_putnlflush(buffer_1);
   else
@@ -16,15 +16,14 @@ void b64encode(const char* c) {
 int main(int argc,char* argv[]) {
   int i;
   for (i=1; i<argc; ++i) {
-    b64encode(argv[i]);
+    b64encode(argv[i],strlen(argv[i]));
   }
   if (argc<2) {
     char src[1024];
     int len;
     while ((len=read(0,src,sizeof(src)-1))>0) {
       if (len==-1) return(1);
-      src[len]=0;
-      b64encode(src);
+      b64encode(src,len);
     }
   }
   return 0;