diff --git a/package.json b/package.json
index 129d07a..64bc01e 100644
--- a/package.json
+++ b/package.json
@@ -36,7 +36,7 @@
     "@babel/polyfill": "^7.0.0",
     "@babel/preset-env": "^7.1.0",
     "@babel/register": "^7.0.0",
-    "ava": "^1.0.0-beta.8",
+    "ava": "^1.4.1",
     "babel-eslint": "^10.0.1",
     "babel-plugin-add-module-exports": "^1.0.0",
     "cross-env": "^5.2.0",
@@ -48,9 +48,9 @@
     "jison-gho": "^0.6.1-215"
   },
   "dependencies": {
-    "postcss": "^7.0.5",
+    "postcss": "^7.0.27",
     "postcss-selector-parser": "^6.0.2",
-    "postcss-value-parser": "^3.3.1"
+    "postcss-value-parser": "^4.0.2"
   },
   "ava": {
     "require": [
diff --git a/src/__tests__/index.js b/src/__tests__/index.js
index 0ae77da..b656c61 100644
--- a/src/__tests__/index.js
+++ b/src/__tests__/index.js
@@ -31,7 +31,8 @@ function testCss(t, fixture, expected = null, opts = {}) {
 async function testThrows(t, fixture, expected, opts) {
   fixture = `foo{bar:${fixture}}`;
 
-  await t.throwsAsync(() => postcss(reduceCalc(opts)).process(fixture, postcssOpts), expected);
+  const error = await t.throwsAsync(() => postcss(reduceCalc(opts)).process(fixture, postcssOpts))
+  t.is(error.message, expected);
 }
 
 test(
@@ -607,7 +608,7 @@ test(
   'should throw an exception when attempting to divide by zero',
   testThrows,
   'calc(500px/0)',
-  /Cannot divide by zero/
+  'Cannot divide by zero'
 );
 
 test(