diff --git a/app/components/add-contribution/component.js b/app/components/add-contribution/component.js
index 19247a8..56de353 100644
--- a/app/components/add-contribution/component.js
+++ b/app/components/add-contribution/component.js
@@ -45,7 +45,9 @@ export default Component.extend({
 
   actions: {
 
-    submit () {
+    submit (evt) {
+      evt.preventDefault();
+
       if (!this.isValid) {
         alert('Invalid data. Please review and try again.');
         return;
diff --git a/app/components/add-contribution/template.hbs b/app/components/add-contribution/template.hbs
index 05fd22e..ab7b930 100644
--- a/app/components/add-contribution/template.hbs
+++ b/app/components/add-contribution/template.hbs
@@ -1,4 +1,4 @@
-<form {{on "submit" this.submit}}>
+<form onsubmit={{action "submit"}}>
   <label>
     <p class="label">Contributor:</p>
     <p>
diff --git a/app/components/add-contributor/component.js b/app/components/add-contributor/component.js
index 346135a..d2a9535 100644
--- a/app/components/add-contributor/component.js
+++ b/app/components/add-contributor/component.js
@@ -7,8 +7,8 @@ import { isAddress } from 'web3-utils';
 
 export default Component.extend({
 
-  kredits: service(),
   router: service(),
+  kredits: service(),
 
   attributes: null,
 
@@ -60,9 +60,15 @@ export default Component.extend({
 
   actions: {
 
-    submit () {
+    submit (evt) {
+      evt.preventDefault();
+
+      if (!this.kredits.currentUserIsCore) {
+        window.alert('Only core team members can edit profiles. Please ask someone to set you up.');
+        return;
+      }
       if (!this.isValid) {
-        alert('Invalid data. Please review and try again.');
+        window.alert('Invalid data. Please review and try again.');
         return;
       }
 
diff --git a/app/components/add-contributor/template.hbs b/app/components/add-contributor/template.hbs
index fc7c22e..140752c 100644
--- a/app/components/add-contributor/template.hbs
+++ b/app/components/add-contributor/template.hbs
@@ -1,4 +1,4 @@
-<form {{on "submit" this.submit}}>
+<form onsubmit={{action "submit"}}>
   <p>
     <label for="c-account">Ethereum account</label>
       <Input @name="account" @id="c-account"
diff --git a/app/components/contribution-list/component.js b/app/components/contribution-list/component.js
index ceebc4a..e297444 100644
--- a/app/components/contribution-list/component.js
+++ b/app/components/contribution-list/component.js
@@ -24,12 +24,10 @@ export default Component.extend({
   contributors: sort('kredits.contributors', 'contributorsSorting'),
 
   contributorsActive: computed('contributors.[]', 'contributions', function() {
-    let activeIds = this.contributions.mapBy('contributorId')
-                                      .map(id => id.toString())
-                                      .uniq();
-    return this.contributors.filter(c => {
-      return activeIds.includes(c.id.toString());
-    });
+    const activeIds = new Set(this.contributions.mapBy('contributorId')
+                                                .map(id => id.toString()));
+
+    return this.contributors.filter(c => activeIds.has(c.id.toString()));
   }),
 
   contributionKinds: computed('contributions.[]', function() {
diff --git a/app/components/contribution-list/template.hbs b/app/components/contribution-list/template.hbs
index f3f4dd8..9656b0f 100644
--- a/app/components/contribution-list/template.hbs
+++ b/app/components/contribution-list/template.hbs
@@ -22,7 +22,7 @@
       </label>
 
       <label class="filter-contribution-size">
-        <Input type="checkbox" @checked={{this.hideSmallContributions}} />
+        <Input @type="checkbox" @checked={{this.hideSmallContributions}} />
         Hide small contributions
       </label>
     </p>
@@ -32,8 +32,8 @@
 <ul class="contribution-list">
   {{#each this.contributionsFiltered as |contribution|}}
     <li role="button" data-contribution-id={{contribution.id}}
-        {{on "click" (fn this.openContributionDetails contribution)}}
-        class="{{contribution-status contribution}}{{if (eq contribution.id @selectedContributionId) " selected"}}">
+        {{action "openContributionDetails" contribution}}
+        class="{{if (eq contribution.id @selectedContributionId) " selected"}}">
       <p class="meta">
         <span class="recipient"><UserAvatar @contributor={{contribution.contributor}} /></span>
         <span class="category {{contribution.kind}}">({{contribution.kind}})</span>
@@ -45,9 +45,9 @@
       {{#unless contribution.vetoed}}
         {{#unless (is-confirmed-contribution contribution)}}
           <p class="voting">
-            <Input @type="button" @class="button small danger" @value="veto"
-                   @click={{fn this.veto contribution.id}}
-                   @disabled={{contribution.hasPendingChanges}} />
+            {{input type="button" class="button small danger" value="veto"
+                    click=(action "veto" contribution.id)
+                    disabled=contribution.hasPendingChanges}}
           </p>
         {{/unless}}
       {{/unless}}
diff --git a/app/components/contributor-list/template.hbs b/app/components/contributor-list/template.hbs
index 95ec449..5149035 100644
--- a/app/components/contributor-list/template.hbs
+++ b/app/components/contributor-list/template.hbs
@@ -1,7 +1,7 @@
 <tbody>
   {{#each @contributorList as |c|}}
     <tr role="button"
-        {{on "click" (fn this.openContributorDetails c.contributor)}}
+        onclick={{action "openContributorDetails" c.contributor}}
         class="{{if (is-current-user c.contributor) "current-user"}} {{if (eq c.contributor.id @selectedContributorId) "selected"}}">
       <td class="person">
         <UserAvatar @contributor={{c.contributor}} /> {{c.contributor.name}}
diff --git a/app/components/topbar-account-panel/template.hbs b/app/components/topbar-account-panel/template.hbs
index f4d8d28..1c113cf 100644
--- a/app/components/topbar-account-panel/template.hbs
+++ b/app/components/topbar-account-panel/template.hbs
@@ -9,9 +9,9 @@
       {{/if}}
     {{else}}
       <span class="anonymous">Anonymous</span>
-      <button {{on "click" this.signup}} class="small" type="button">Sign up</button>
+      <button onclick={{action "signup"}} class="small" type="button">Sign up</button>
       {{#if this.showConnectButton}}
-        <button {{on "click" this.connectAccount}} class="small green" type="button">Connect account</button>
+        <button onclick={{action "connectAccount"}} class="small green" type="button">Connect account</button>
       {{/if}}
     {{/if}}
   {{/if}}
diff --git a/app/templates/dashboard/contributors/show.hbs b/app/templates/dashboard/contributors/show.hbs
index 241de86..4686f70 100644
--- a/app/templates/dashboard/contributors/show.hbs
+++ b/app/templates/dashboard/contributors/show.hbs
@@ -10,7 +10,7 @@
     <ul class="external-accounts">
       {{#each this.model.accounts as |account|}}
         <li>
-          <ExternalAccountLink @account={{this.account}} />
+          <ExternalAccountLink @account={{account}} />
         </li>
       {{/each}}
       {{#if this.model.url}}
diff --git a/app/templates/signup/eth-account.hbs b/app/templates/signup/eth-account.hbs
index 7f100e9..d5091c3 100644
--- a/app/templates/signup/eth-account.hbs
+++ b/app/templates/signup/eth-account.hbs
@@ -16,7 +16,7 @@
   </form>
   <p class="actions">
     <button disabled={{this.signupButtonDisabled}}
-            {{on "click" this.completeSignup}}
+            onclick={{action "completeSignup"}}
             type="button">
       Complete my profile
     </button>
diff --git a/app/templates/signup/index.hbs b/app/templates/signup/index.hbs
index 036384d..5d68d22 100644
--- a/app/templates/signup/index.hbs
+++ b/app/templates/signup/index.hbs
@@ -12,7 +12,7 @@
     connecting one of the following accounts:
   </p>
   <p class="actions">
-    <button {{on "click" this.connectGithub}} class="icon" type="button">
+    <button onclick={{action "connectGithub"}} class="icon" type="button">
       <IconAccountGithubCom />
       Connect GitHub
     </button>