diff --git a/package-lock.json b/package-lock.json
index c36463d..a93e12c 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@solid/jose",
-  "version": "0.6.9",
+  "version": "0.7.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@solid/jose",
-      "version": "0.6.9",
+      "version": "0.7.0",
       "license": "MIT",
       "dependencies": {
         "@sinonjs/text-encoding": "^0.7.2",
diff --git a/package.json b/package.json
index dc0405d..793be96 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@solid/jose",
-  "version": "0.6.9",
+  "version": "0.7.0",
   "description": "JSON Object Signing and Encryption",
   "main": "src/index.js",
   "directories": {
diff --git a/src/algorithms/index.js b/src/algorithms/index.js
index 5dff01b..e91b742 100644
--- a/src/algorithms/index.js
+++ b/src/algorithms/index.js
@@ -64,8 +64,23 @@ supportedAlgorithms.define('ES256', 'sign', new ECDSA({
   },
   namedCurve: 'P-256'
 }))
-//supportedAlgorithms.define('ES384', 'sign', {})
-//supportedAlgorithms.define('ES512', 'sign', {})
+
+supportedAlgorithms.define('ES384', 'sign', new ECDSA({
+  name: 'ECDSA',
+  hash: {
+    name: 'SHA-384'
+  },
+  namedCurve: 'P-384'
+}))
+
+supportedAlgorithms.define('ES512', 'sign', new ECDSA({
+  name: 'ECDSA',
+  hash: {
+    name: 'SHA-512'
+  },
+  namedCurve: 'P-521'
+}))
+
 //supportedAlgorithms.define('PS256', 'sign', {})
 //supportedAlgorithms.define('PS384', 'sign', {})
 //supportedAlgorithms.define('PS512', 'sign', {})
@@ -126,8 +141,23 @@ supportedAlgorithms.define('ES256', 'verify', new ECDSA({
   },
   namedCurve: 'P-256'
 }))
-//supportedAlgorithms.define('ES384', 'verify', {})
-//supportedAlgorithms.define('ES512', 'verify', {})
+
+supportedAlgorithms.define('ES384', 'verify', new ECDSA({
+  name: 'ECDSA',
+  hash: {
+    name: 'SHA-384'
+  },
+  namedCurve: 'P-384'
+}))
+
+supportedAlgorithms.define('ES512', 'verify', new ECDSA({
+  name: 'ECDSA',
+  hash: {
+    name: 'SHA-512'
+  },
+  namedCurve: 'P-521'
+}))
+
 //supportedAlgorithms.define('PS256', 'verify', {})
 //supportedAlgorithms.define('PS384', 'verify', {})
 //supportedAlgorithms.define('PS512', 'verify', {})
@@ -165,6 +195,22 @@ supportedAlgorithms.define('ES256', 'importKey', new ECDSA({
   namedCurve: 'P-256'
 }))
 
+supportedAlgorithms.define('ES384', 'importKey', new ECDSA({
+  name: 'ECDSA',
+  hash: {
+    name: 'SHA-384'
+  },
+  namedCurve: 'P-384'
+}))
+
+supportedAlgorithms.define('ES512', 'importKey', new ECDSA({
+  name: 'ECDSA',
+  hash: {
+    name: 'SHA-512'
+  },
+  namedCurve: 'P-521'
+}))
+
 /**
  * Export
  */
diff --git a/src/jose/JWA.js b/src/jose/JWA.js
index 69a9b11..a237917 100644
--- a/src/jose/JWA.js
+++ b/src/jose/JWA.js
@@ -87,6 +87,11 @@ class JWA {
    */
   static async importKey (key) {
     let normalizedAlgorithm = supportedAlgorithms.normalize('importKey', key.alg)
+
+    if (normalizedAlgorithm instanceof Error) {
+      return Promise.reject(new NotSupportedError(key.alg))
+    }
+
     return normalizedAlgorithm.importKey(key)
   }
 }