diff --git a/.gitignore b/.gitignore
index c043cd1c..952193be 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,6 @@
 build
 node_modules
-coverage
+/coverage
 test/bench/node_modules
 test/fixtures/output*
 test/leak/libvips.supp
diff --git a/package.json b/package.json
index 0f10b954..41294e16 100644
--- a/package.json
+++ b/package.json
@@ -45,6 +45,7 @@
   "scripts": {
     "clean": "rm -rf node_modules/ build/ vendor/ coverage/ test/fixtures/output.*",
     "test": "semistandard && cc && nyc --reporter=lcov --branches=99 mocha --slow=5000 --timeout=60000 ./test/unit/*.js",
+    "coverage": "./test/coverage/report.sh",
     "test-leak": "./test/leak/leak.sh",
     "docs": "for m in constructor input resize composite operation colour channel output utility; do documentation build --shallow --format=md lib/$m.js >docs/api-$m.md; done"
   },
@@ -74,7 +75,7 @@
     "nan": "^2.8.0",
     "semver": "^5.4.1",
     "simple-get": "^2.7.0",
-    "tar": "^4.0.1",
+    "tar": "^4.1.1",
     "tunnel-agent": "^0.6.0"
   },
   "devDependencies": {
@@ -84,7 +85,7 @@
     "exif-reader": "^1.0.2",
     "icc": "^1.0.0",
     "mocha": "^4.0.1",
-    "nyc": "^11.3.0",
+    "nyc": "^11.4.0",
     "rimraf": "^2.6.1",
     "semistandard": "^11.0.0",
     "unzip": "^0.1.11"
diff --git a/test/coverage/report.sh b/test/coverage/report.sh
new file mode 100755
index 00000000..1c0b5459
--- /dev/null
+++ b/test/coverage/report.sh
@@ -0,0 +1,6 @@
+#!/bin/sh
+
+CPPFLAGS="--coverage" LDFLAGS="--coverage" npm rebuild
+npm test
+geninfo --no-external --base-directory src --output-file coverage/sharp.info build/Release/obj.target/sharp/src
+genhtml --title sharp --demangle-cpp --output-directory coverage/sharp coverage/*.info