diff --git a/Lib/doctest.py b/Lib/doctest.py
index 3f2baa5..aeeb15d 100644
--- a/Lib/doctest.py
+++ b/Lib/doctest.py
@@ -844,6 +844,8 @@
             globs = globs.copy()
         if extraglobs is not None:
             globs.update(extraglobs)
+        if '__name__' not in globs:
+            globs['__name__'] = '__main__'  # provide a default module name
 
         # Recursively expore `obj`, extracting DocTests.
         tests = []
@@ -1937,6 +1939,8 @@
         globs = globs.copy()
     if extraglobs is not None:
         globs.update(extraglobs)
+    if '__name__' not in globs:
+        globs['__name__'] = '__main__'
 
     if raise_on_error:
         runner = DebugRunner(verbose=verbose, optionflags=optionflags)