diff --git a/Lib/bdb.py b/Lib/bdb.py
index dacbcc0..8f808cc 100644
--- a/Lib/bdb.py
+++ b/Lib/bdb.py
@@ -178,9 +178,13 @@
         self.returnframe = frame
         self.quitting = 0
 
-    def set_trace(self):
-        """Start debugging from here."""
-        frame = sys._getframe().f_back
+    def set_trace(self, frame=None):
+        """Start debugging from `frame`.
+
+        If frame is not specified, debugging starts from caller's frame.
+        """
+        if frame is None:
+            frame = sys._getframe().f_back
         self.reset()
         while frame:
             frame.f_trace = self.trace_dispatch
diff --git a/Lib/pdb.py b/Lib/pdb.py
index b608adf..7b5dffa 100755
--- a/Lib/pdb.py
+++ b/Lib/pdb.py
@@ -997,7 +997,7 @@
     return Pdb().runcall(*args, **kwds)
 
 def set_trace():
-    Pdb().set_trace()
+    Pdb().set_trace(sys._getframe().f_back)
 
 # Post-Mortem interface