diff --git a/babi/file.py b/babi/file.py
index 0e9d216..fd99b74 100644
--- a/babi/file.py
+++ b/babi/file.py
@@ -707,7 +707,10 @@ class File:
     def _comment_add(self, lineno: int, prefix: str, s_offset: int) -> None:
         line = self.buf[lineno]
 
-        self.buf[lineno] = f'{line[:s_offset]}{prefix} {line[s_offset:]}'
+        if not line:
+            self.buf[lineno] = f'{prefix}'
+        else:
+            self.buf[lineno] = f'{line[:s_offset]}{prefix} {line[s_offset:]}'
 
         if lineno == self.buf.y and self.buf.x > s_offset:
             self.buf.x += len(self.buf[lineno]) - len(line)
diff --git a/tests/features/comment_test.py b/tests/features/comment_test.py
index 37efc5b..c5e38e2 100644
--- a/tests/features/comment_test.py
+++ b/tests/features/comment_test.py
@@ -21,6 +21,20 @@ def test_comment_some_code(run, ten_lines):
         h.await_text('# line_0\n# line_1\nline_2\n')
 
 
+def test_comment_empty_line_trailing_whitespace(run, tmpdir):
+    f = tmpdir.join('f')
+    f.write('1\n\n2\n')
+
+    with run(str(f)) as h, and_exit(h):
+        h.press('S-Down')
+        h.press('S-Down')
+
+        trigger_command_mode(h)
+        h.press_and_enter(':comment')
+
+        h.await_text('# 1\n#\n# 2')
+
+
 def test_comment_some_code_with_alternate_comment_character(run, ten_lines):
     with run(str(ten_lines)) as h, and_exit(h):
         h.press('S-Down')