diff --git a/avocado/utils/kernel.py b/avocado/utils/kernel.py
index 235353973d7cfd0976c28877f64766eddefb5e33..a953e90a825b9f97729a9c5f83fda845558b3bd2 100644
--- a/avocado/utils/kernel.py
+++ b/avocado/utils/kernel.py
@@ -63,6 +63,12 @@ class KernelBuild(object):
                                               self.config_path,
                                               self.work_dir)
 
+    def _build_kernel_url(self, base_url=None):
+        kernel_file = self.SOURCE.format(version=self.version)
+        if base_url is None:
+            base_url = self.URL.format(major=self.version.split('.', 1)[0])
+        return base_url + kernel_file
+
     def download(self, url=None):
         """
         Download kernel source.
@@ -71,19 +77,7 @@ class KernelBuild(object):
                     source tarball
         :type url: str or None
         """
-
-        kernel_file = self.SOURCE.format(version=self.version)
-        # if there's no url to override, the default is the one
-        # specified in the class
-        if url is None:
-            base_url = self.URL.format(major=self.version.split('.', 1)[0])
-
-        # however, if there's a url informed as a parameter, this one
-        # should be used as the base url.
-        else:
-            base_url = url
-        full_url = base_url + kernel_file
-
+        full_url = self._build_kernel_url(base_url=url)
         self.asset_path = asset.Asset(full_url, asset_hash=None,
                                       algorithm=None, locations=None,
                                       cache_dirs=self.data_dirs).fetch()
diff --git a/selftests/unit/test_utils_kernel.py b/selftests/unit/test_utils_kernel.py
new file mode 100644
index 0000000000000000000000000000000000000000..b9ecbcfcc1071b7d7b02fa0e310c5755720d5f28
--- /dev/null
+++ b/selftests/unit/test_utils_kernel.py
@@ -0,0 +1,18 @@
+import unittest
+
+from avocado.utils.kernel import KernelBuild
+
+
+class TestKernelBuild(unittest.TestCase):
+    def setUp(self):
+        self.kernel_version = '4.4.133'
+        self.kernel = KernelBuild(self.kernel_version)
+
+    def test_build_default_url(self):
+        expected_url = 'https://www.kernel.org/pub/linux/kernel/v4.x/linux-4.4.133.tar.gz'
+        self.assertEqual(self.kernel._build_kernel_url(), expected_url)
+
+    def test_build_overrided_url(self):
+        base_url = 'https://mykernel.com/'
+        expected_url = '{}linux-4.4.133.tar.gz'.format(base_url)
+        self.assertEqual(self.kernel._build_kernel_url(base_url=base_url), expected_url)