diff --git a/Lib/multiprocessing/forking.py b/Lib/multiprocessing/forking.py
index 3fca8b1..55980ff 100644
--- a/Lib/multiprocessing/forking.py
+++ b/Lib/multiprocessing/forking.py
@@ -336,7 +336,7 @@
         '''
         Returns prefix of command line used for spawning a child process
         '''
-        if process.current_process()._identity==() and is_forking(sys.argv):
+        if getattr(process.current_process(), '_inheriting', False):
             raise RuntimeError('''
             Attempt to start a new process before the current process
             has finished its bootstrapping phase.