diff --git a/tqdm/tests/tests_tqdm.py b/tqdm/tests/tests_tqdm.py
index e8dc7592..20821ac9 100644
--- a/tqdm/tests/tests_tqdm.py
+++ b/tqdm/tests/tests_tqdm.py
@@ -209,6 +209,15 @@ def test_format_interval():
     assert format_interval(238113) == '66:08:33'
 
 
+def test_format_num():
+    """Test number format"""
+    format_num = tqdm.format_num
+
+    assert float(format_num(1337)) == 1337
+    assert format_num(int(1e6)) == '1e+6'
+    assert format_num(1239876) == '1''239''876'
+
+
 def test_format_meter():
     """Test statistics and progress bar formatting"""
     try: