diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b0b211518..e886b69de 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -83,9 +83,11 @@ jobs:
   tag-semver:
     runs-on: ubuntu-latest
     steps:
-      - name: Checkout
+      -
+        name: Checkout
         uses: actions/checkout@v2
-      - name: Docker meta
+      -
+        name: Docker meta
         uses: ./
         with:
           images: |
diff --git a/__tests__/meta.test.ts b/__tests__/meta.test.ts
index d46501117..dfe08ad54 100644
--- a/__tests__/meta.test.ts
+++ b/__tests__/meta.test.ts
@@ -737,6 +737,32 @@ describe('push tag', () => {
         "org.opencontainers.image.licenses=MIT"
       ]
     ],
+    [
+      'event_tag_sometag.env',
+      {
+        images: ['ghcr.io/user/app'],
+        tagSemver: ['{{version}}', '{{major}}.{{minor}}', '{{major}}'],
+      } as Inputs,
+      {
+        main: 'sometag',
+        partial: [],
+        latest: true
+      } as Version,
+      [
+        'ghcr.io/user/app:sometag',
+        'ghcr.io/user/app:latest',
+      ],
+      [
+        "org.opencontainers.image.title=Hello-World",
+        "org.opencontainers.image.description=This your first repo!",
+        "org.opencontainers.image.url=https://github.com/octocat/Hello-World",
+        "org.opencontainers.image.source=https://github.com/octocat/Hello-World",
+        "org.opencontainers.image.version=sometag",
+        "org.opencontainers.image.created=2020-01-10T00:30:00.000Z",
+        "org.opencontainers.image.revision=90dd6032fac8bda1b6c4436a2e65de27961ed071",
+        "org.opencontainers.image.licenses=MIT"
+      ]
+    ],
   ])('given %p event ', tagsLabelsTest);
 });
 
diff --git a/dist/index.js b/dist/index.js
index 686da3e95..85e11d328 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -171,6 +171,7 @@ exports.Meta = void 0;
 const handlebars = __webpack_require__(7492);
 const moment = __webpack_require__(9623);
 const semver = __webpack_require__(1383);
+const core = __webpack_require__(2186);
 class Meta {
     constructor(inputs, context, repo) {
         this.inputs = inputs;
@@ -198,6 +199,9 @@ class Meta {
         }
         else if (/^refs\/tags\//.test(this.context.ref)) {
             version.main = this.context.ref.replace(/^refs\/tags\//g, '').replace(/\//g, '-');
+            if (this.inputs.tagSemver.length > 0 && !semver.valid(version.main)) {
+                core.warning(`${version.main} is not a valid semver. More info: https://semver.org/`);
+            }
             if (this.inputs.tagSemver.length > 0 && semver.valid(version.main)) {
                 const sver = semver.parse(version.main, {
                     includePrerelease: true
diff --git a/src/meta.ts b/src/meta.ts
index 9f838fd04..f8ee02abb 100644
--- a/src/meta.ts
+++ b/src/meta.ts
@@ -2,6 +2,7 @@ import * as handlebars from 'handlebars';
 import * as moment from 'moment';
 import * as semver from 'semver';
 import {Inputs} from './context';
+import * as core from '@actions/core';
 import {Context} from '@actions/github/lib/context';
 import {ReposGetResponseData} from '@octokit/types';
 
@@ -46,6 +47,9 @@ export class Meta {
       });
     } else if (/^refs\/tags\//.test(this.context.ref)) {
       version.main = this.context.ref.replace(/^refs\/tags\//g, '').replace(/\//g, '-');
+      if (this.inputs.tagSemver.length > 0 && !semver.valid(version.main)) {
+        core.warning(`${version.main} is not a valid semver. More info: https://semver.org/`);
+      }
       if (this.inputs.tagSemver.length > 0 && semver.valid(version.main)) {
         const sver = semver.parse(version.main, {
           includePrerelease: true