diff --git a/lib/versioning/docker/index.js b/lib/versioning/docker/index.js
index 1124b4f4d564f9138196361305f8b107393e0dd8..92a0592e7f080ada864187c1768a711c9e3b36da 100644
--- a/lib/versioning/docker/index.js
+++ b/lib/versioning/docker/index.js
@@ -52,6 +52,9 @@ function isLessThanRange(version, range) {
   return compare(version, range) < 0;
 }
 function isValid(version) {
+  if (!version) {
+    return null;
+  }
   const parsed = parse(version);
   return parsed ? version : null;
 }
diff --git a/test/versioning/docker.spec.js b/test/versioning/docker.spec.js
index 72acd0755e8258248c501a22e3e75b818c963f1d..cc5e6db0485688144aed263b3b9365e3a4ba828f 100644
--- a/test/versioning/docker.spec.js
+++ b/test/versioning/docker.spec.js
@@ -4,6 +4,7 @@ const semver = require('../../lib/versioning')('semver');
 describe('docker.isValid(input)', () => {
   describe('isValid(version)', () => {
     it('should support all versions length', () => {
+      expect(docker.isValid(null)).toBe(null);
       expect(docker.isValid('1.2.3')).toBe('1.2.3');
       expect(docker.isValid('18.04')).toBe('18.04');
       expect(docker.isValid('10.1')).toBe('10.1');
@@ -11,7 +12,7 @@ describe('docker.isValid(input)', () => {
       expect(docker.isValid('foo')).toBe(null);
     });
   });
-  describe('isValid(version)', () => {
+  describe('getMajor(version)', () => {
     it('should support all versions length', () => {
       expect(docker.getMajor('1.2.3')).toBe(1);
       expect(docker.getMajor('18.04')).toBe(18);