diff --git a/libvips/foreign/webpsave.c b/libvips/foreign/webpsave.c
index 5b945a60..9afda455 100644
--- a/libvips/foreign/webpsave.c
+++ b/libvips/foreign/webpsave.c
@@ -397,6 +397,8 @@ vips_foreign_save_webp_buffer_build( VipsObject *object )
 	g_object_set( buffer, "buffer", blob, NULL );
 	vips_area_unref( VIPS_AREA( blob ) );
 
+	VIPS_UNREF( streamo );
+
 	return( 0 );
 }
 
diff --git a/test/test-suite/test_arithmetic.py b/test/test-suite/test_arithmetic.py
index b965991c..5d18e8e0 100644
--- a/test/test-suite/test_arithmetic.py
+++ b/test/test-suite/test_arithmetic.py
@@ -41,6 +41,12 @@ class TestArithmetic:
         cls.mono = cls.colour.extract_band(1)
         cls.all_images = [cls.mono, cls.colour]
 
+    @classmethod
+    def teardown_class(cls):
+        cls.colour = None
+        cls.mono = None
+        cls.all_images = None
+
     # test all operator overloads we define
 
     def test_add(self):
diff --git a/test/test-suite/test_conversion.py b/test/test-suite/test_conversion.py
index 0ee88574..c26f7b06 100644
--- a/test/test-suite/test_conversion.py
+++ b/test/test-suite/test_conversion.py
@@ -44,6 +44,13 @@ class TestConversion:
         cls.all_images = [cls.mono, cls.colour]
         cls.image = pyvips.Image.jpegload(JPEG_FILE)
 
+    @classmethod
+    def teardown_class(cls):
+        cls.colour = None
+        cls.mono = None
+        cls.image = None
+        cls.all_images = None
+
     def test_band_and(self):
         def band_and(x):
             if isinstance(x, pyvips.Image):
diff --git a/test/test-suite/test_convolution.py b/test/test-suite/test_convolution.py
index 1778c5c2..54fc0bb3 100644
--- a/test/test-suite/test_convolution.py
+++ b/test/test-suite/test_convolution.py
@@ -55,6 +55,17 @@ class TestConvolution:
                                                  [-1, -2, -1]])
         cls.all_masks = [cls.sharp, cls.blur, cls.line, cls.sobel]
 
+    @classmethod
+    def teardown_class(cls):
+        cls.colour = None
+        cls.mono = None
+        cls.all_images = None
+        cls.sharp = None
+        cls.blur = None
+        cls.line = None
+        cls.sobel = None
+        cls.all_masks = None
+
     def test_conv(self):
         for im in self.all_images:
             for msk in self.all_masks:
diff --git a/test/test-suite/test_foreign.py b/test/test-suite/test_foreign.py
index 94b4336b..3d9b6b90 100644
--- a/test/test-suite/test_foreign.py
+++ b/test/test-suite/test_foreign.py
@@ -38,6 +38,11 @@ class TestForeign:
     @classmethod
     def teardown_class(cls):
         shutil.rmtree(cls.tempdir, ignore_errors=True)
+        cls.colour = None
+        cls.mono = None
+        cls.rad = None
+        cls.cmyk = None
+        cls.onebit = None
 
     # we have test files for formats which have a clear standard
     def file_loader(self, loader, test_file, validate):
diff --git a/test/test-suite/test_stream.py b/test/test-suite/test_stream.py
index 4d7c9978..d7ce0c89 100644
--- a/test/test-suite/test_stream.py
+++ b/test/test-suite/test_stream.py
@@ -37,6 +37,10 @@ class TestStream:
     @classmethod
     def teardown_class(cls):
         shutil.rmtree(cls.tempdir, ignore_errors=True)
+        cls.colour = None
+        cls.mono = None
+        cls.rad = None
+        cls.cmyk = None
 
     def test_streami_new_from_file(self):
         x = pyvips.Streami.new_from_file(JPEG_FILE)