diff --git a/test/leak/leak.sh b/test/leak/leak.sh
index dc4c09ee..98c96eb3 100755
--- a/test/leak/leak.sh
+++ b/test/leak/leak.sh
@@ -7,12 +7,14 @@ fi
 
 curl -o ./test/leak/libvips.supp https://raw.githubusercontent.com/jcupitt/libvips/master/libvips.supp
 
-G_SLICE=always-malloc G_DEBUG=gc-friendly valgrind \
-  --suppressions=test/leak/libvips.supp \
-  --suppressions=test/leak/sharp.supp \
-  --gen-suppressions=yes \
-  --leak-check=full \
-  --show-leak-kinds=definite,indirect,possible \
-  --num-callers=20 \
-  --trace-children=yes \
-  npm test
+for test in ./test/unit/*.js; do
+  G_SLICE=always-malloc G_DEBUG=gc-friendly valgrind \
+    --suppressions=test/leak/libvips.supp \
+    --suppressions=test/leak/sharp.supp \
+    --gen-suppressions=yes \
+    --leak-check=full \
+    --show-leak-kinds=definite,indirect,possible \
+    --num-callers=20 \
+    --trace-children=yes \
+    mocha --slow=60000 --timeout=120000 "$test";
+done
diff --git a/test/leak/sharp.supp b/test/leak/sharp.supp
index 9c01c400..4e8c0dc9 100644
--- a/test/leak/sharp.supp
+++ b/test/leak/sharp.supp
@@ -156,10 +156,27 @@
   fun:vips_region_generate
 }
 {
-  cond_libvips_col_sRGB2scRGB_8
+  value_libvips_col_sRGB2scRGB_8
   Memcheck:Value8
   fun:vips_col_sRGB2scRGB_8
 }
+{
+  value_libvips_col_sRGB2scRGB_line_8
+  Memcheck:Value8
+  fun:vips_sRGB2scRGB_line_8
+}
+{
+  value_libvips_write_webp
+  Memcheck:Value8
+  ...
+  fun:write_webp.constprop.1
+  fun:vips__webp_write_buffer
+}
+{
+  cond_libvips_vips_cast_gen
+  Memcheck:Cond
+  fun:vips_cast_gen
+}
 {
   cond_libvips_vips_region_fill
   Memcheck:Cond
@@ -270,6 +287,20 @@
   ...
   fun:_ZN4node17CreateEnvironmentEPN2v87IsolateEP9uv_loop_sNS0_5LocalINS0_7ContextEEEiPKPKciSB_
 }
+{
+  leak_nodejs_Environment_Start
+  Memcheck:Leak
+  match-leak-kinds: possible
+  ...
+  fun:_ZN4node11Environment5StartEiPKPKciS4_b
+}
+{
+  leak_nodejs_node9inspector5Agent5Start
+  Memcheck:Leak
+  match-leak-kinds: possible
+  ...
+  fun:_ZN4node9inspector5Agent5StartEPN2v88PlatformEPKcRKNS_12DebugOptionsE
+}
 {
   leak_nodejs_icu_getAvailableLocales
   Memcheck:Leak
@@ -365,3 +396,10 @@
   ...
   fun:_ZN2v88internal8Malloced3NewEm
 }
+{
+  leak_v8_inspector10toString
+  Memcheck:Leak
+  match-leak-kinds: possible
+  ...
+  fun:_ZN12v8_inspector10toString16ERKNS_10StringViewE
+}