diff --git a/src/ol/AssertionError.js b/src/ol/AssertionError.js
index d7f09b8242..2ecaf6db7d 100644
--- a/src/ol/AssertionError.js
+++ b/src/ol/AssertionError.js
@@ -72,7 +72,7 @@ class AssertionError extends Error {
    * @param {number} code Error code.
    */
   constructor(code) {
-    const message = `Assertion failed. ${messages[code]}.`;
+    const message = messages[code];
 
     super(message);
 
diff --git a/test/node/ol/AssertionError.test.js b/test/node/ol/AssertionError.test.js
index 6ea4290e3b..b64ca33394 100644
--- a/test/node/ol/AssertionError.test.js
+++ b/test/node/ol/AssertionError.test.js
@@ -9,9 +9,7 @@ describe('ol/AssertionError.js', function () {
 
   it('generates a message with a versioned url', function () {
     const error = new AssertionError(42);
-    expect(error.message).to.be(
-      'Assertion failed. Question unknown, the answer is 42.'
-    );
+    expect(error.message).to.be('Question unknown, the answer is 42');
   });
 
   it('has an error code', function () {