Index: Lib/pdb.py
===================================================================
--- Lib/pdb.py	(revision 77684)
+++ Lib/pdb.py	(working copy)
@@ -1218,7 +1218,7 @@
         self._wait_for_mainpyfile = 1
         self.mainpyfile = self.canonic(filename)
         self._user_requested_quit = 0
-        statement = 'execfile( "%s")' % filename
+        statement = 'execfile(%r)' % filename
         self.run(statement)
 
 # Simplified interface
Index: Lib/test/test_pdb.py
===================================================================
--- Lib/test/test_pdb.py	(revision 77684)
+++ Lib/test/test_pdb.py	(working copy)
@@ -5,6 +5,8 @@
 import os
 import sys
 import doctest
+import unittest
+import subprocess
 import tempfile
 
 from test import test_support
@@ -128,7 +130,29 @@
     (Pdb) continue
     """
 
+class Tester7750(unittest.TestCase):
+    # if the filename has something that resolves to a python
+    #  escape character (such as \t), it will fail
+    test_fn = '.\\test7750.py'
 
+    msg = "issue7750 only applies when os.sep is a backslash"
+    @unittest.skipUnless(os.path.sep == '\\', msg)
+    def test_issue7750(self):
+        with open(self.test_fn, 'w') as f:
+            f.write('print("hello world")')
+        cmd = [sys.executable, '-m', 'pdb', self.test_fn,]
+        proc = subprocess.Popen(cmd,
+            stdout=subprocess.PIPE,
+            stdin=subprocess.PIPE,
+            stderr=subprocess.STDOUT,
+            )
+        stdout, stderr = proc.communicate('quit\n')
+        self.assertNotIn('IOError', stdout, "pdb munged the filename")
+
+    def tearDown(self):
+        if os.path.isfile(self.test_fn):
+            os.remove(self.test_fn)
+
 def test_main():
     from test import test_pdb
     test_support.run_doctest(test_pdb, verbosity=True)
@@ -136,3 +160,4 @@
 
 if __name__ == '__main__':
     test_main()
+    unittest.main()