diff --git a/coverage/pytracer.py b/coverage/pytracer.py
index f0319491d..1f0f79249 100644
--- a/coverage/pytracer.py
+++ b/coverage/pytracer.py
@@ -159,6 +159,8 @@ def _trace(self, frame, event, arg_unused):
                 if tracename not in self.data:
                     self.data[tracename] = set()
                 self.cur_file_data = self.data[tracename]
+            else:
+                frame.f_trace_lines = False
             # The call event is really a "start frame" event, and happens for
             # function calls and re-entering generators.  The f_lasti field is
             # -1 for calls, and a real offset for generators.  Use <0 as the