diff --git a/IPython/core/interactiveshell.py b/IPython/core/interactiveshell.py
index d6a6557..46e423f 100644
--- a/IPython/core/interactiveshell.py
+++ b/IPython/core/interactiveshell.py
@@ -2075,10 +2075,21 @@ class InteractiveShell(SingletonConfigurable, Magic):
         cmd : str
           Command to execute.
         """
+        cmd = self.var_expand(cmd, depth=2)
+        # protect os.system from UNC paths on Windows, which it can't handle:
+        if sys.platform == 'win32':
+            from IPython.utils._process_win32 import AvoidUNCPath
+            with AvoidUNCPath() as path:
+                if path is not None:
+                    cmd = '"pushd %s &&"%s' % (path, cmd)
+                ec = os.system(cmd)
+        else:
+            ec = os.system(cmd)
+        
         # We explicitly do NOT return the subprocess status code, because
         # a non-None value would trigger :func:`sys.displayhook` calls.
         # Instead, we store the exit_code in user_ns.
-        self.user_ns['_exit_code'] = os.system(self.var_expand(cmd, depth=2))
+        self.user_ns['_exit_code'] = ec
 
     # use piped system by default, because it is better behaved
     system = system_piped
diff --git a/IPython/frontend/terminal/interactiveshell.py b/IPython/frontend/terminal/interactiveshell.py
index a57ecca..fbfe89c 100644
--- a/IPython/frontend/terminal/interactiveshell.py
+++ b/IPython/frontend/terminal/interactiveshell.py
@@ -112,11 +112,9 @@ class TerminalInteractiveShell(InteractiveShell):
             config=config, profile_dir=profile_dir, user_ns=user_ns,
             user_global_ns=user_global_ns, custom_exceptions=custom_exceptions
         )
-        # use os.system instead of utils.process.system by default, except on Windows
-        if os.name == 'nt':
-            self.system = self.system_piped
-        else:
-            self.system = self.system_raw
+        # use os.system instead of utils.process.system by default,
+        # because piped system doesn't make sense in the Terminal:
+        self.system = self.system_raw
 
         self.init_term_title()
         self.init_usage(usage)