diff --git a/test/python/flowmetal/test_parser.py b/test/python/flowmetal/test_parser.py
index 7665e1f..bac2344 100644
--- a/test/python/flowmetal/test_parser.py
+++ b/test/python/flowmetal/test_parser.py
@@ -15,13 +15,20 @@ def test_parse_list():
     assert p.parses("()").paren == p.ListType.ROUND
 
 
-@pytest.mark.parametrize('num,', [
-    1, 2, 103, 504,
+@pytest.mark.parametrize('txt, val', [
+    ('1', 1),
+    ('2', 2),
+    ('103', 103),
+    ('504', 504),
+    ('-1', -1),
+    ('+1', +1),
+    ('+1_000', 1000),
+    ('-1_000', -1000),
 ])
-def test_parse_num(num):
+def test_parse_num(txt, val):
     """Some trivial cases of parsing numbers."""
-    assert isinstance(p.parses(str(num)), p.IntegerToken)
-    assert p.parses(str(num)).data == num
+    assert isinstance(p.parses(txt), p.IntegerToken)
+    assert p.parses(txt).data == val
 
 
 @pytest.mark.parametrize('frac', [
@@ -33,8 +40,13 @@ def test_parse_ratio(frac):
     assert p.parses(frac).data == p.Fraction(frac)
 
 
+
 @pytest.mark.parametrize('sym,', [
-    'a', 'b', '*earmuff-style*', '+kebab-style+', 'JAVA_CONSTANT_STYLE'
+    'a',
+    'b',
+    '*earmuff-style*',
+    '+kebab-style+',
+    'JAVA_CONSTANT_STYLE',
 ])
 def test_parse_sym(sym):
     """Some trivial cases of parsing symbols."""
@@ -76,6 +88,7 @@ def test_list_contents(txt, tokenization):
     ('1e3', 1e3),
     ('1e-3', 1e-3),
     ('1.01e3', 1.01e3),
+    ('1_000e0', 1e3),
 ])
 def test_float_values(txt, value):
     """Some examples of floats."""