diff --git a/ChangeLog b/ChangeLog
index 3c99096a..3bc532e6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -15,6 +15,7 @@
 
 31/8/19 started 8.8.3
 - revert sharpen restoring the input colourspace
+- xres/yres tiffsave params were in pixels/cm [f--f]
 
 9/7/19 started 8.8.2
 - better early shutdown in readers
diff --git a/libvips/convolution/sharpen.c b/libvips/convolution/sharpen.c
index 795299a6..72b0a509 100644
--- a/libvips/convolution/sharpen.c
+++ b/libvips/convolution/sharpen.c
@@ -41,7 +41,6 @@
  * 	- move to defaults suitable for screen output
  * 28/8/19
  * 	- fix sigma 0.5 case (thanks 2h4dl)
- * 	- restore input colourspace
  */
 
 /*
diff --git a/libvips/foreign/tiffsave.c b/libvips/foreign/tiffsave.c
index b1e45d85..341193cc 100644
--- a/libvips/foreign/tiffsave.c
+++ b/libvips/foreign/tiffsave.c
@@ -17,6 +17,8 @@
  * 8/7/19
  * 	- add webp and zstd support
  * 	- add @level and @lossless
+ * 4/9/18 [f--f]
+ * 	- xres/yres params were in pixels/cm
  */
 
 /*
@@ -142,16 +144,22 @@ vips_foreign_save_tiff_build( VipsObject *object )
 		build( object ) )
 		return( -1 );
 
-	/* Default xres/yres to the values from the image.
+	/* Default xres/yres to the values from the image. This is always
+	 * pixels/mm.
 	 */
 	if( !vips_object_argument_isset( object, "xres" ) )
-		tiff->xres = save->ready->Xres * 10.0;
+		tiff->xres = save->ready->Xres;
 	if( !vips_object_argument_isset( object, "yres" ) )
-		tiff->yres = save->ready->Yres * 10.0;
+		tiff->yres = save->ready->Yres;
+
+	/* We default to pixels/cm.
+	 */
+	tiff->xres *= 10.0;
+	tiff->yres *= 10.0;
 
 	/* resunit param overrides resunit metadata.
 	 */
-	if( !vips_object_argument_isset( object, "resunit" ) &&
+	if( vips_object_argument_isset( object, "resunit" ) &&
 		vips_image_get_typeof( save->ready, 
 			VIPS_META_RESOLUTION_UNIT ) &&
 		!vips_image_get_string( save->ready, 
diff --git a/test/test-suite/test_foreign.py b/test/test-suite/test_foreign.py
index 6856418c..6af9654a 100644
--- a/test/test-suite/test_foreign.py
+++ b/test/test-suite/test_foreign.py
@@ -321,6 +321,24 @@ class TestForeign:
         assert x1.width == x2.height
         assert x1.height == x2.width
 
+        filename = temp_filename(self.tempdir, '.tif')
+        x = pyvips.Image.new_from_file(TIF_FILE)
+        x = x.copy()
+        x.write_to_file(filename, xres=100, yres=200, resunit="cm")
+        x1 = pyvips.Image.new_from_file(filename)
+        assert x1.get("resolution-unit") == "cm"
+        assert x1.xres == 100
+        assert x1.yres == 200
+
+        filename = temp_filename(self.tempdir, '.tif')
+        x = pyvips.Image.new_from_file(TIF_FILE)
+        x = x.copy()
+        x.write_to_file(filename, xres=100, yres=200, resunit="inch")
+        x1 = pyvips.Image.new_from_file(filename)
+        assert x1.get("resolution-unit") == "in"
+        assert x1.xres == 100
+        assert x1.yres == 200
+
         # OME support in 8.5
         x = pyvips.Image.new_from_file(OME_FILE)
         assert x.width == 439