diff --git a/e2e_toy/tests/test_textops.py b/e2e_toy/tests/test_textops.py
index e05680d..f59d90e 100644
--- a/e2e_toy/tests/test_textops.py
+++ b/e2e_toy/tests/test_textops.py
@@ -10,10 +10,10 @@ def test_single_spaces(self):
 
 class SlugifyTest(unittest.TestCase):
     def test_basic(self):
-        self.assertEqual(slugify("Hello World"), "hello-world")
+        self.assertEqual(slugify("Hello World"), "hello_world")
 
     def test_extra_spaces(self):
-        self.assertEqual(slugify("  Hello   World "), "hello-world")
+        self.assertEqual(slugify("  Hello   World "), "hello_world")
 
 
 class ClampTest(unittest.TestCase):
diff --git a/e2e_toy/textops.py b/e2e_toy/textops.py
index 8f71f6c..321484b 100644
--- a/e2e_toy/textops.py
+++ b/e2e_toy/textops.py
@@ -10,9 +10,11 @@ def word_count(text):
 
 
 def slugify(text):
-    """Lowercase ``text`` and join its words with single dashes."""
-    words = [w for w in text.lower().split() if w]
-    return "-".join(words)
+    """Lowercase ``text`` and join its words with single separators."""
+    return _SEPARATOR.join(text.lower().split())
+
+
+_SEPARATOR = "_"
 
 
 def clamp(value, low, high):