diff --git a/src/black/lines.py b/src/black/lines.py
index b2bdcc441b4..fb5933ecbfb 100644
--- a/src/black/lines.py
+++ b/src/black/lines.py
@@ -598,7 +598,7 @@ def _maybe_empty_lines(self, current_line: Line) -> Tuple[int, int]:
                     before = 1
                 elif (
                     not depth
-                    and self.previous_defs[-1]
+                    and self.previous_defs[-1].depth
                     and current_line.leaves[-1].type == token.COLON
                     and (
                         current_line.leaves[0].value