diff --git a/libvips/foreign/vips2jpeg.c b/libvips/foreign/vips2jpeg.c
index e2172cf3..f645fa6b 100644
--- a/libvips/foreign/vips2jpeg.c
+++ b/libvips/foreign/vips2jpeg.c
@@ -845,8 +845,7 @@ write_jpeg_block( VipsRegion *region, VipsRect *area, void *a )
 		write->row_pointer[i] = (JSAMPROW) 
 			VIPS_REGION_ADDR( region, 0, area->top + i );
 
-	/* We are running in a background thread. We need to catch any
-	 * longjmp()s from jpeg_write_scanlines() here.
+	/* Catch any longjmp()s from jpeg_write_scanlines() here.
 	 */
 	if( setjmp( write->eman.jmp ) ) 
 		return( -1 );
diff --git a/test/test_foreign.py b/test/test_foreign.py
index 52e95165..85b66834 100755
--- a/test/test_foreign.py
+++ b/test/test_foreign.py
@@ -50,6 +50,10 @@ class TestForeign(unittest.TestCase):
         self.cmyk = self.colour.bandjoin(self.mono)
         self.cmyk = self.cmyk.copy(interpretation = Vips.Interpretation.CMYK)
 
+	# this will load via libMagick as a colour image
+        im = Vips.Image.new_from_file(self.gif_file)
+        self.onebit = im[1] > 128
+
     # we have test files for formats which have a clear standard
     def file_loader(self, loader, test_file, validate):
         im = Vips.call(loader, test_file)
@@ -144,6 +148,11 @@ class TestForeign(unittest.TestCase):
         self.save_load("%s.tif", self.colour)
         self.save_load("%s.tif", self.cmyk)
 
+        self.save_load("%s.tif", self.onebit)
+        self.save_load("%s.tif[squash]", self.onebit)
+        self.save_load("%s.tif[miniswhite]", self.onebit)
+        self.save_load("%s.tif[squash,miniswhite]", self.onebit)
+
         self.save_load_file("test.tif", "[tile]", self.colour, 0)
         self.save_load_file("test.tif", "[tile,pyramid]", self.colour, 0)
         self.save_load_file("test.tif",