diff --git a/src/js_regex/_impl.py b/src/js_regex/_impl.py
index 22931d3..ea75b1e 100644
--- a/src/js_regex/_impl.py
+++ b/src/js_regex/_impl.py
@@ -55,8 +55,8 @@ def compile(pattern, flags=0):
         (r"\a", "\a"),
         (r"\d", "[0-9]"),
         (r"\D", "[^0-9]"),
-        (r"\w", "[A-Za-z]"),
-        (r"\W", "[^A-Za-z]"),
+        (r"\w", "[A-Za-z0-9_]"),
+        (r"\W", "[^A-Za-z0-9_]"),
         (r"\s", "[ \t\n\r\x0b\x0c]"),
         (r"\S", "[^ \t\n\r\x0b\x0c]"),
     ]:
diff --git a/test_js_regex.py b/test_js_regex.py
index 79e1b6e..6166e3b 100644
--- a/test_js_regex.py
+++ b/test_js_regex.py
@@ -32,6 +32,23 @@
 def test_expected_transforms(pattern, good_match, bad_match):
     regex = js_regex.compile(pattern)
     assert regex.search(good_match)
+    assert len(regex.findall(good_match)) == 1
+    assert not regex.search(bad_match)
+
+
+@pytest.mark.parametrize(
+    "pattern,good_match,bad_match",
+    [
+        ("^abc\n$", "abc\n", "abc"),
+        ("^abc$|^def$", "abc", "abc\n"),
+        ("^abc$|^def$", "def", "def\n"),
+        (r"^abc\$", "abc$", "abc"),
+    ],
+)
+def test_expected_multiline_transforms(pattern, good_match, bad_match):
+    regex = js_regex.compile(pattern, re.MULTILINE)
+    assert regex.search(good_match)
+    assert len(regex.findall(good_match)) == 1
     assert not regex.search(bad_match)
 
 
@@ -41,6 +58,8 @@ def test_expected_transforms(pattern, good_match, bad_match):
         pytest.param(r"\d", "1", "߀", marks=SKIP_ON_PY2),  # NKO DIGIT ZERO
         (r"\D", "߀", "1"),
         pytest.param(r"\w", "a", "é", marks=SKIP_ON_PY2),  # Latin-1 e-acute
+        (r"\w", "1", "߀"),
+        (r"\w", "_", "/"),
         (r"\W", "é", "a"),
         pytest.param(r"\s", "\t", "\xa0", marks=SKIP_ON_PY2),  # non-breaking space
         (r"\S", "\xa0", "\t"),