diff --git a/test/Makefile.am b/test/Makefile.am
index 241981d0..60aac2b0 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -1,5 +1,6 @@
 # don't run test_thumbnail.sh by default, it takes ages
 TESTS = \
+	test_streams.sh \
 	test_descriptors.sh \
 	test_cli.sh \
 	test_formats.sh \
@@ -10,11 +11,15 @@ SUBDIRS = \
 	test-suite 
 
 noinst_PROGRAMS = \
-	test_descriptors
+	test_descriptors \
+	test_streams
 
 test_descriptors_SOURCES = \
 	test_descriptors.c
 
+test_streams_SOURCES = \
+	test_streams.c 
+
 AM_CPPFLAGS = -I${top_srcdir}/libvips/include @VIPS_CFLAGS@ @VIPS_INCLUDES@
 AM_LDFLAGS = @LDFLAGS@ 
 LDADD = @VIPS_CFLAGS@ ${top_builddir}/libvips/libvips.la @VIPS_LIBS@
@@ -22,6 +27,8 @@ LDADD = @VIPS_CFLAGS@ ${top_builddir}/libvips/libvips.la @VIPS_LIBS@
 EXTRA_DIST = \
 	variables.sh.in \
 	test_cli.sh \
+	test_descriptors.sh \
+	test_streams.sh \
 	test_formats.sh \
 	test_seq.sh \
 	test_thumbnail.sh \
diff --git a/test/test_formats.sh b/test/test_formats.sh
index 96992123..4d7b8319 100755
--- a/test/test_formats.sh
+++ b/test/test_formats.sh
@@ -51,30 +51,6 @@ save_load() {
 	fi
 }
 
-# is a difference beyond a threshold? return 0 (meaning all ok) or 1 (meaning
-# error, or outside threshold)
-break_threshold() {
-	diff=$1
-	threshold=$2
-	return $(echo "$diff <= $threshold" | bc -l)
-}
-
-# subtract, look for max difference less than a threshold
-test_difference() {
-	before=$1
-	after=$2
-	threshold=$3
-
-	$vips subtract $before $after $tmp/difference.v
-	$vips abs $tmp/difference.v $tmp/abs.v 
-	dif=$($vips max $tmp/abs.v)
-
-	if break_threshold $dif $threshold; then
-		echo "save / load difference is $dif"
-		exit 1
-	fi
-}
-
 # save to the named file in tmp, convert back to vips again, subtract, look
 # for max difference less than a threshold
 test_format() {
diff --git a/test/test_streams b/test/test_streams
new file mode 100755
index 00000000..b7e8f017
--- /dev/null
+++ b/test/test_streams
@@ -0,0 +1,210 @@
+#! /bin/bash
+
+# test_streams - temporary wrapper script for .libs/test_streams
+# Generated by libtool (GNU libtool) 2.4.6 Debian-2.4.6-11
+#
+# The test_streams program cannot be directly executed until all the libtool
+# libraries that it depends on are installed.
+#
+# This wrapper script should never be moved out of the build directory.
+# If it is, it will not operate correctly.
+
+# Sed substitution that helps us do robust quoting.  It backslashifies
+# metacharacters that are still active within double-quoted strings.
+sed_quote_subst='s|\([`"$\\]\)|\\\1|g'
+
+# Be Bourne compatible
+if test -n "${ZSH_VERSION+set}" && (emulate sh) >/dev/null 2>&1; then
+  emulate sh
+  NULLCMD=:
+  # Zsh 3.x and 4.x performs word splitting on ${1+"$@"}, which
+  # is contrary to our usage.  Disable this feature.
+  alias -g '${1+"$@"}'='"$@"'
+  setopt NO_GLOB_SUBST
+else
+  case `(set -o) 2>/dev/null` in *posix*) set -o posix;; esac
+fi
+BIN_SH=xpg4; export BIN_SH # for Tru64
+DUALCASE=1; export DUALCASE # for MKS sh
+
+# The HP-UX ksh and POSIX shell print the target directory to stdout
+# if CDPATH is set.
+(unset CDPATH) >/dev/null 2>&1 && unset CDPATH
+
+relink_command=""
+
+# This environment variable determines our operation mode.
+if test "$libtool_install_magic" = "%%%MAGIC variable%%%"; then
+  # install mode needs the following variables:
+  generated_by_libtool_version='2.4.6'
+  notinst_deplibs=' ../libvips/libvips.la'
+else
+  # When we are sourced in execute mode, $file and $ECHO are already set.
+  if test "$libtool_execute_magic" != "%%%MAGIC variable%%%"; then
+    file="$0"
+
+# A function that is used when there is no print builtin or printf.
+func_fallback_echo ()
+{
+  eval 'cat <<_LTECHO_EOF
+$1
+_LTECHO_EOF'
+}
+    ECHO="printf %s\\n"
+  fi
+
+# Very basic option parsing. These options are (a) specific to
+# the libtool wrapper, (b) are identical between the wrapper
+# /script/ and the wrapper /executable/ that is used only on
+# windows platforms, and (c) all begin with the string --lt-
+# (application programs are unlikely to have options that match
+# this pattern).
+#
+# There are only two supported options: --lt-debug and
+# --lt-dump-script. There is, deliberately, no --lt-help.
+#
+# The first argument to this parsing function should be the
+# script's ../libtool value, followed by no.
+lt_option_debug=
+func_parse_lt_options ()
+{
+  lt_script_arg0=$0
+  shift
+  for lt_opt
+  do
+    case "$lt_opt" in
+    --lt-debug) lt_option_debug=1 ;;
+    --lt-dump-script)
+        lt_dump_D=`$ECHO "X$lt_script_arg0" | /bin/sed -e 's/^X//' -e 's%/[^/]*$%%'`
+        test "X$lt_dump_D" = "X$lt_script_arg0" && lt_dump_D=.
+        lt_dump_F=`$ECHO "X$lt_script_arg0" | /bin/sed -e 's/^X//' -e 's%^.*/%%'`
+        cat "$lt_dump_D/$lt_dump_F"
+        exit 0
+      ;;
+    --lt-*)
+        $ECHO "Unrecognized --lt- option: '$lt_opt'" 1>&2
+        exit 1
+      ;;
+    esac
+  done
+
+  # Print the debug banner immediately:
+  if test -n "$lt_option_debug"; then
+    echo "test_streams:test_streams:$LINENO: libtool wrapper (GNU libtool) 2.4.6 Debian-2.4.6-11" 1>&2
+  fi
+}
+
+# Used when --lt-debug. Prints its arguments to stdout
+# (redirection is the responsibility of the caller)
+func_lt_dump_args ()
+{
+  lt_dump_args_N=1;
+  for lt_arg
+  do
+    $ECHO "test_streams:test_streams:$LINENO: newargv[$lt_dump_args_N]: $lt_arg"
+    lt_dump_args_N=`expr $lt_dump_args_N + 1`
+  done
+}
+
+# Core function for launching the target application
+func_exec_program_core ()
+{
+
+      if test -n "$lt_option_debug"; then
+        $ECHO "test_streams:test_streams:$LINENO: newargv[0]: $progdir/$program" 1>&2
+        func_lt_dump_args ${1+"$@"} 1>&2
+      fi
+      exec "$progdir/$program" ${1+"$@"}
+
+      $ECHO "$0: cannot exec $program $*" 1>&2
+      exit 1
+}
+
+# A function to encapsulate launching the target application
+# Strips options in the --lt-* namespace from $@ and
+# launches target application with the remaining arguments.
+func_exec_program ()
+{
+  case " $* " in
+  *\ --lt-*)
+    for lt_wr_arg
+    do
+      case $lt_wr_arg in
+      --lt-*) ;;
+      *) set x "$@" "$lt_wr_arg"; shift;;
+      esac
+      shift
+    done ;;
+  esac
+  func_exec_program_core ${1+"$@"}
+}
+
+  # Parse options
+  func_parse_lt_options "$0" ${1+"$@"}
+
+  # Find the directory that this script lives in.
+  thisdir=`$ECHO "$file" | /bin/sed 's%/[^/]*$%%'`
+  test "x$thisdir" = "x$file" && thisdir=.
+
+  # Follow symbolic links until we get to the real thisdir.
+  file=`ls -ld "$file" | /bin/sed -n 's/.*-> //p'`
+  while test -n "$file"; do
+    destdir=`$ECHO "$file" | /bin/sed 's%/[^/]*$%%'`
+
+    # If there was a directory component, then change thisdir.
+    if test "x$destdir" != "x$file"; then
+      case "$destdir" in
+      [\\/]* | [A-Za-z]:[\\/]*) thisdir="$destdir" ;;
+      *) thisdir="$thisdir/$destdir" ;;
+      esac
+    fi
+
+    file=`$ECHO "$file" | /bin/sed 's%^.*/%%'`
+    file=`ls -ld "$thisdir/$file" | /bin/sed -n 's/.*-> //p'`
+  done
+
+  # Usually 'no', except on cygwin/mingw when embedded into
+  # the cwrapper.
+  WRAPPER_SCRIPT_BELONGS_IN_OBJDIR=no
+  if test "$WRAPPER_SCRIPT_BELONGS_IN_OBJDIR" = "yes"; then
+    # special case for '.'
+    if test "$thisdir" = "."; then
+      thisdir=`pwd`
+    fi
+    # remove .libs from thisdir
+    case "$thisdir" in
+    *[\\/].libs ) thisdir=`$ECHO "$thisdir" | /bin/sed 's%[\\/][^\\/]*$%%'` ;;
+    .libs )   thisdir=. ;;
+    esac
+  fi
+
+  # Try to get the absolute directory name.
+  absdir=`cd "$thisdir" && pwd`
+  test -n "$absdir" && thisdir="$absdir"
+
+  program='test_streams'
+  progdir="$thisdir/.libs"
+
+
+  if test -f "$progdir/$program"; then
+    # Add our own library path to LD_LIBRARY_PATH
+    LD_LIBRARY_PATH="/home/john/GIT/libvips/libvips/.libs:/usr/lib/x86_64-linux-gnu:$LD_LIBRARY_PATH"
+
+    # Some systems cannot cope with colon-terminated LD_LIBRARY_PATH
+    # The second colon is a workaround for a bug in BeOS R4 sed
+    LD_LIBRARY_PATH=`$ECHO "$LD_LIBRARY_PATH" | /bin/sed 's/::*$//'`
+
+    export LD_LIBRARY_PATH
+
+    if test "$libtool_execute_magic" != "%%%MAGIC variable%%%"; then
+      # Run the actual program with our arguments.
+      func_exec_program ${1+"$@"}
+    fi
+  else
+    # The program doesn't exist.
+    $ECHO "$0: error: '$progdir/$program' does not exist" 1>&2
+    $ECHO "This script is just a wrapper for $program." 1>&2
+    $ECHO "See the libtool documentation for more information." 1>&2
+    exit 1
+  fi
+fi
diff --git a/test/test_streams.c b/test/test_streams.c
new file mode 100644
index 00000000..4c48bc94
--- /dev/null
+++ b/test/test_streams.c
@@ -0,0 +1,151 @@
+/* Test stream*u.
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <vips/vips.h>
+
+typedef struct _MyInput {
+	const char *filename; 
+	const unsigned char *contents; 
+	size_t length;
+	size_t read_position;
+} MyInput;
+
+typedef struct _MyOutput {
+	const char *filename; 
+	int fd;
+} MyOutput;
+
+static gint64
+read_cb( VipsStreamiu *streamiu, 
+	void *buffer, gint64 length, MyInput *my_input )
+{
+	gint64 bytes_read = VIPS_MIN( length, 
+		my_input->length - my_input->read_position );
+
+	/*
+	printf( "read_cb: buffer = 0x%p, length = %zd\n", buffer, length );
+	 */
+
+	memcpy( buffer, 
+		my_input->contents + my_input->read_position, bytes_read );
+	my_input->read_position += bytes_read;
+
+	return( bytes_read );
+}
+
+static gint64
+seek_cb( VipsStreamiu *streamiu, 
+	gint64 offset, int whence, MyInput *my_input )
+{
+	gint64 new_pos;
+
+	/*
+	printf( "seek_cb: offset = %zd, whence = %d\n", offset, whence );
+	 */
+
+	switch( whence ) {
+	case SEEK_SET:
+		new_pos = offset;
+		break;
+
+	case SEEK_CUR:
+		new_pos = my_input->read_position + offset;
+		break;
+
+	case SEEK_END:
+		new_pos = my_input->length + offset;
+		break;
+
+	default:
+		vips_error( "demo", "%s", "bad 'whence'" );
+		return( -1 );
+	}
+
+	my_input->read_position = VIPS_CLIP( 0, new_pos, my_input->length );
+
+	return( my_input->read_position );
+}
+
+static gint64
+write_cb( VipsStreamou *streamou, 
+	const void *data, gint64 length, MyOutput *my_output )
+{
+	gint64 bytes_written;
+
+	/*
+	printf( "write_cb: data = 0x%p, length = %zd\n", data, length );
+	 */
+
+	bytes_written = write( my_output->fd, data, length );
+
+	return( bytes_written );
+}
+
+static void
+finish_cb( VipsStreamou *streamou, MyOutput *my_output ) 
+{
+	/*
+	printf( "finish_cb:\n" );
+	 */
+
+	close( my_output->fd );
+	my_output->fd = -1;
+}
+
+int
+main( int argc, char **argv )
+{
+	MyInput my_input;
+	MyOutput my_output;
+	VipsStreamiu *streamiu;
+	VipsStreamou *streamou;
+	VipsImage *image;
+
+	if( VIPS_INIT( NULL ) )
+		return( -1 );
+
+	my_input.filename = argv[1];
+	my_input.contents = NULL;
+	my_input.length = 0;
+	my_input.read_position = 0;
+
+	if( !g_file_get_contents( my_input.filename, 
+		(char **) &my_input.contents, &my_input.length, NULL ) ) 
+		vips_error_exit( "unable to load from %s", my_input.filename );
+
+	streamiu = vips_streamiu_new();
+	g_signal_connect( streamiu, "seek", G_CALLBACK( seek_cb ), &my_input );
+	g_signal_connect( streamiu, "read", G_CALLBACK( read_cb ), &my_input );
+
+	if( !(image = vips_image_new_from_stream( VIPS_STREAMI( streamiu ), "",
+		"access", VIPS_ACCESS_SEQUENTIAL,
+		NULL )) ) 
+		vips_error_exit( NULL );
+
+	my_output.filename = argv[2];
+	my_output.fd = -1;
+
+	if( (my_output.fd = vips__open( my_output.filename, 
+		O_WRONLY | O_CREAT | O_TRUNC, 0644 )) == -1 )
+		vips_error_exit( "unable to save to %s", my_output.filename );
+
+	streamou = vips_streamou_new();
+	g_signal_connect( streamou, "write",
+		G_CALLBACK( write_cb ), &my_output );
+	g_signal_connect( streamou, "finish", 
+		G_CALLBACK( finish_cb ), &my_output );
+
+	if( vips_image_write_to_stream( image, ".png", 
+		VIPS_STREAMO( streamou ), NULL ) ) 
+		vips_error_exit( NULL );
+
+	VIPS_UNREF( image );
+	VIPS_UNREF( streamiu );
+	VIPS_UNREF( streamou );
+
+	return( 0 );
+}
diff --git a/test/test_streams.sh b/test/test_streams.sh
new file mode 100755
index 00000000..c0a578e5
--- /dev/null
+++ b/test/test_streams.sh
@@ -0,0 +1,15 @@
+#!/bin/sh
+
+# test load and save via stream*u
+
+# set -x
+set -e
+
+. ./variables.sh
+
+if test_supported jpegload_stream; then
+	./test_streams $image $tmp/x.png
+
+	# test max difference < 10
+	test_difference $image $tmp/x.png 10
+fi
diff --git a/test/variables.sh.in b/test/variables.sh.in
index 0e4c3136..a949c74a 100644
--- a/test/variables.sh.in
+++ b/test/variables.sh.in
@@ -25,3 +25,27 @@ test_supported() {
 
 	return $result
 }
+
+# is a difference beyond a threshold? return 0 (meaning all ok) or 1 (meaning
+# error, or outside threshold)
+break_threshold() {
+	diff=$1
+	threshold=$2
+	return $(echo "$diff <= $threshold" | bc -l)
+}
+
+# subtract, look for max difference less than a threshold
+test_difference() {
+	before=$1
+	after=$2
+	threshold=$3
+
+	$vips subtract $before $after $tmp/difference.v
+	$vips abs $tmp/difference.v $tmp/abs.v 
+	dif=$($vips max $tmp/abs.v)
+
+	if break_threshold $dif $threshold; then
+		echo "save / load difference is $dif"
+		exit 1
+	fi
+}