diff --git a/easybuild/framework/easyblock.py b/easybuild/framework/easyblock.py
index 4f04cdabe7..b5a4bab879 100644
--- a/easybuild/framework/easyblock.py
+++ b/easybuild/framework/easyblock.py
@@ -2382,7 +2382,7 @@ def guess_start_dir(self):
                 # make sure start_dir subdir exists (cfr. check below)
                 mkdir(os.path.join(topdir, start_dir), parents=True)
 
-            abs_start_dir = os.path.join(topdir, start_dir)
+            abs_start_dir = os.path.join(topdir, start_dir) if start_dir else topdir
             if topdir.endswith(start_dir) and not os.path.exists(abs_start_dir):
                 self.cfg['start_dir'] = topdir
             else:
diff --git a/test/framework/easyblock.py b/test/framework/easyblock.py
index c818dd7187..f05a354050 100644
--- a/test/framework/easyblock.py
+++ b/test/framework/easyblock.py
@@ -2845,6 +2845,8 @@ def check_start_dir(expected_start_dir):
             abs_expected_start_dir = os.path.join(eb.builddir, expected_start_dir)
             self.assertTrue(os.path.samefile(eb.cfg['start_dir'], abs_expected_start_dir))
             self.assertTrue(os.path.samefile(os.getcwd(), abs_expected_start_dir))
+            self.assertTrue(eb.cfg['start_dir'].endswith(abs_expected_start_dir))
+            self.assertFalse(eb.cfg['start_dir'].endswith(os.path.sep))
 
         # default (no start_dir specified): use unpacked dir as start dir
         self.assertEqual(ec['ec']['start_dir'], None)
diff --git a/test/framework/easyconfig.py b/test/framework/easyconfig.py
index 9dddc29f46..86465456b6 100644
--- a/test/framework/easyconfig.py
+++ b/test/framework/easyconfig.py
@@ -1510,8 +1510,8 @@ def test_start_dir_template(self):
             eb.run_all_steps(False)
         logtxt = read_file(eb.logfile)
         start_dir = os.path.join(eb.builddir, 'toy-0.0')
-        self.assertIn('start_dir in configure is %s/ &&' % start_dir, logtxt)
-        self.assertIn('start_dir in build is %s/ &&' % start_dir, logtxt)
+        self.assertIn('start_dir in configure is %s &&' % start_dir, logtxt)
+        self.assertIn('start_dir in build is %s &&' % start_dir, logtxt)
         ext_start_dir = os.path.join(eb.builddir, 'bar', 'bar-0.0')
         self.assertIn('start_dir in extension configure is %s &&' % ext_start_dir, logtxt)
         self.assertIn('start_dir in extension build is %s &&' % ext_start_dir, logtxt)