diff --git a/letters/tests/test_views.py b/letters/tests/test_views.py
index 71abee4..2eb3fb8 100644
--- a/letters/tests/test_views.py
+++ b/letters/tests/test_views.py
@@ -720,6 +720,11 @@ def test_highlight_for_sentiment(self, mock_highlight_for_custom_sentiment, mock
                     "highlight_for_sentiment() shouldn't call mock_highlight_text_for_sentiment() if sentiment_id isn't 0")
         mock_highlight_for_custom_sentiment.reset_mock()
 
+        # If text is empty, highlight_for_custom_sentiment() should not be called
+        highlight_for_sentiment('', 1)
+        self.assertEqual(mock_highlight_for_custom_sentiment.call_count, 0,
+                         'If text is empty, highlight_for_custom_sentiment() should not be called')
+
 
 class SearchViewTestCase(TestCase):
     """
diff --git a/letters/views.py b/letters/views.py
index 8d236ae..a3b1f6a 100644
--- a/letters/views.py
+++ b/letters/views.py
@@ -376,6 +376,9 @@ def highlight_for_sentiment(text, sentiment_id):
     if sentiment_id == 0:
         return [mark_safe(highlight) for highlight in highlight_text_for_sentiment(text)]
 
+    if not text:
+        return ['']
+
     return [mark_safe(highlight_for_custom_sentiment(text, sentiment_id))]