diff --git a/Lib/test/test_zipimport.py b/Lib/test/test_zipimport.py
index e31e217..b435b32 100644
--- a/Lib/test/test_zipimport.py
+++ b/Lib/test/test_zipimport.py
@@ -395,59 +395,144 @@
     def setUp(self):
         zipimport._zip_directory_cache.clear()
         zipimport._zip_stat_cache.clear()
+        # save sys.modules so we can unimport everything done by our tests.
+        self._sys_modules_orig = dict(sys.modules)
         ImportHooksBaseTestCase.setUp(self)
 
     def tearDown(self):
         ImportHooksBaseTestCase.tearDown(self)
+        # The closest we can come to un-importing our zipped up test modules.
+        sys.modules.clear()
+        sys.modules.update(self._sys_modules_orig)
         if os.path.exists(TEMP_ZIP):
             os.remove(TEMP_ZIP)
 
-    def testZipFileChangesAfterFirstImport(self):
-        """Alter the zip file after caching its index and try an import."""
+    def setUpZipFileModuleAndTestImports(self):
+        # Create a .zip file to test with
+        self.zipfile_path = TEMP_ZIP
         packdir = TESTPACK + os.sep
         files = {packdir + "__init__" + pyc_ext: (NOW, test_pyc),
                  packdir + TESTMOD + ".py": (NOW, "test_value = 38\n"),
                  "ziptest_a.py": (NOW, "test_value = 23\n"),
                  "ziptest_b.py": (NOW, "test_value = 42\n"),
                  "ziptest_c.py": (NOW, "test_value = 1337\n")}
-        zipfile_path = TEMP_ZIP
-        _write_zip_package(zipfile_path, files)
-        self.assertTrue(os.path.exists(zipfile_path))
-        sys.path.insert(0, zipfile_path)
+        _write_zip_package(self.zipfile_path, files)
+        self.assertTrue(os.path.exists(self.zipfile_path))
+        sys.path.insert(0, self.zipfile_path)
+
+        self.testpack_testmod = TESTPACK + "." + TESTMOD
+
+        with io.open(self.zipfile_path, "rb") as orig_zip_file:
+            self.orig_zip_file_contents = orig_zip_file.read()
 
         # Import something out of the zipfile and confirm it is correct.
-        testmod = __import__(TESTPACK + "." + TESTMOD,
+        testmod = __import__(self.testpack_testmod,
                              globals(), locals(), ["__dummy__"])
         self.assertEqual(testmod.test_value, 38)
+        del sys.modules[TESTPACK]
+        del sys.modules[self.testpack_testmod]
+
         # Import something else out of the zipfile and confirm it is correct.
         ziptest_b = __import__("ziptest_b", globals(), locals(), ["test_value"])
         self.assertEqual(ziptest_b.test_value, 42)
+        del sys.modules["ziptest_b"]
 
-        # Truncate and fill the zip file with non-zip garbage.
-        with io.open(zipfile_path, "rb") as orig_zip_file:
-            orig_zip_file_contents = orig_zip_file.read()
-        with io.open(zipfile_path, "wb") as byebye_valid_zip_file:
+    def truncateAndFillZipWithNonZipGarbage(self):
+        with io.open(self.zipfile_path, "wb") as byebye_valid_zip_file:
             byebye_valid_zip_file.write(b"Tear down this wall!\n"*1987)
+
+    def restoreZipFileWithDifferentHeaderOffsets(self):
+        """Make it a valid zipfile with some garbage at the start."""
+        # This alters all of the caches offsets within the file.
+        with io.open(self.zipfile_path, "wb") as new_zip_file:
+            new_zip_file.write(b"X"*1991)  # The year Python was created.
+            new_zip_file.write(self.orig_zip_file_contents)
+
+    def testZipFileChangesAfterFirstImport(self):
+        """Alter the zip file after caching its index and try an import."""
+        self.setUpZipFileModuleAndTestImports()
+        # The above call cached the .zip table of contents during its tests.
+        self.truncateAndFillZipWithNonZipGarbage()
         # Now that the zipfile has been replaced, import something else from it
         # which should fail as the file contents are now garbage.
         with self.assertRaises(ImportError):
             ziptest_a = __import__("ziptest_a", globals(), locals(),
                                    ["test_value"])
+        # The code path used by the __import__ call is different than
+        # that used by import statements.  Try these as well.  Some of
+        # these may create new zipimporter instances.  We need to
+        # function properly using the global zipimport caches
+        # regardless of how many zipimporter instances for the same
+        # .zip file exist.
+        with self.assertRaises(ImportError):
+            import ziptest_a
+        with self.assertRaises(ImportError):
+            from ziptest_a import test_value
+        with self.assertRaises(ImportError):
+            exec("from {} import {}".format(TESTPACK, TESTMOD))
 
-        # Now lets make it a valid zipfile that has some garbage at the start.
-        # This alters all of the offsets within the file
-        with io.open(zipfile_path, "wb") as new_zip_file:
-            new_zip_file.write(b"X"*1991)  # The year Python was created.
-            new_zip_file.write(orig_zip_file_contents)
+        # Alters all of the offsets within the file
+        self.restoreZipFileWithDifferentHeaderOffsets()
 
         # Now that the zip file has been "restored" to a valid but different
-        # zipfile the zipimporter should *successfully* re-read the new zip
-        # file's end of file central index and be able to import from it again.
+        # zipfile all zipimporter instances should *successfully* re-read the
+        # new file's end of file central index and be able to import again.
+
+        # Importing a submodule triggers a different import code path.
+        exec("import " + self.testpack_testmod)
+        self.assertEqual(getattr(locals()[TESTPACK], TESTMOD).test_value, 38)
+        exec("from {} import {}".format(TESTPACK, TESTMOD))
+        self.assertEqual(locals()[TESTMOD].test_value, 38)
+
         ziptest_a = __import__("ziptest_a", globals(), locals(), ["test_value"])
         self.assertEqual(ziptest_a.test_value, 23)
         ziptest_c = __import__("ziptest_c", globals(), locals(), ["test_value"])
         self.assertEqual(ziptest_c.test_value, 1337)
 
+    def testZipFileSubpackageImport(self):
+        """Import via multiple sys.path entries into parts of the zip."""
+        self.setUpZipFileModuleAndTestImports()
+        # Put a subdirectory within the zip file into the import path.
+        sys.path.insert(0, self.zipfile_path + os.sep + TESTPACK)
+
+        testmod = __import__(TESTMOD, globals(), locals(), ["test_value"])
+        self.assertEqual(testmod.test_value, 38)
+        del sys.modules[TESTMOD]
+        exec("from {} import test_value".format(TESTMOD))
+        self.assertEqual(test_value, 38)
+        del sys.modules[TESTMOD]
+
+        # Confirm that imports from the top level of the zip file
+        # (already in sys.path from the setup call above) still work.
+        ziptest_a = __import__("ziptest_a", globals(), locals(), ["test_value"])
+        self.assertEqual(ziptest_a.test_value, 23)
+        del sys.modules["ziptest_a"]
+        import ziptest_c
+        self.assertEqual(ziptest_c.test_value, 1337)
+        del sys.modules["ziptest_c"]
+
+        self.truncateAndFillZipWithNonZipGarbage()
+        # Imports should now fail.
+        with self.assertRaises(ImportError):
+            testmod = __import__(TESTMOD, globals(), locals(), ["test_value"])
+        with self.assertRaises(ImportError):
+            exec("from {} import test_value".format(TESTMOD))
+        with self.assertRaises(ImportError):
+            import ziptest_a
+
+        self.restoreZipFileWithDifferentHeaderOffsets()
+        # Imports should work again, the central directory TOC will be re-read.
+        testmod = __import__(TESTMOD, globals(), locals(), ["test_value"])
+        self.assertEqual(testmod.test_value, 38)
+        del sys.modules[TESTMOD]
+        exec("from {} import test_value".format(TESTMOD))
+        self.assertEqual(test_value, 38)
+
+        ziptest_a = __import__("ziptest_a", globals(), locals(), ["test_value"])
+        self.assertEqual(ziptest_a.test_value, 23)
+        import ziptest_c
+        self.assertEqual(ziptest_c.test_value, 1337)
+
 
 class BadFileZipImportTestCase(unittest.TestCase):
     def assertZipFailure(self, filename):
diff --git a/Modules/zipimport.c b/Modules/zipimport.c
index 24439e0..180b56f 100644
--- a/Modules/zipimport.c
+++ b/Modules/zipimport.c
@@ -66,30 +66,34 @@
 static int
 zipimporter_init(ZipImporter *self, PyObject *args, PyObject *kwds)
 {
-    char *path, *p, *prefix, buf[MAXPATHLEN+2];
+    char *path_arg, *path, *p, *prefix, *path_buf;
     size_t len;
 
     if (!_PyArg_NoKeywords("zipimporter()", kwds))
         return -1;
 
-    if (!PyArg_ParseTuple(args, "s:zipimporter",
-                          &path))
+    if (!PyArg_ParseTuple(args, "s:zipimporter", &path_arg))
         return -1;
 
-    len = strlen(path);
+    len = strlen(path_arg);
     if (len == 0) {
         PyErr_SetString(ZipImportError, "archive path is empty");
         return -1;
     }
     if (len >= MAXPATHLEN) {
-        PyErr_SetString(ZipImportError,
-                        "archive path too long");
+        PyErr_SetString(ZipImportError, "archive path too long");
         return -1;
     }
-    strcpy(buf, path);
+    /* Room for the trailing \0 and room for an extra SEP if needed. */
+    path_buf = (char *)PyMem_Malloc(len + 2);
+    if (path_buf == NULL) {
+        PyErr_SetString(PyExc_MemoryError, "unable to malloc path buffer");
+        return -1;
+    }
+    strcpy(path_buf, path_arg);
 
 #ifdef ALTSEP
-    for (p = buf; *p; p++) {
+    for (p = path_buf; *p; p++) {
         if (*p == ALTSEP)
             *p = SEP;
     }
@@ -102,25 +106,25 @@
         struct stat statbuf;
         int rv;
 
-        rv = stat(buf, &statbuf);
+        rv = stat(path_buf, &statbuf);
         if (rv == 0) {
             /* it exists */
             if (S_ISREG(statbuf.st_mode))
                 /* it's a file */
-                path = buf;
+                path = path_buf;
             break;
         }
 #else
-        if (object_exists(buf)) {
+        if (object_exists(path_buf)) {
             /* it exists */
-            if (isfile(buf))
+            if (isfile(path_buf))
                 /* it's a file */
-                path = buf;
+                path = path_buf;
             break;
         }
 #endif
         /* back up one path element */
-        p = strrchr(buf, SEP);
+        p = strrchr(path_buf, SEP);
         if (prefix != NULL)
             *prefix = SEP;
         if (p == NULL)
@@ -130,48 +134,52 @@
     }
     if (path != NULL) {
         PyObject *files;
+        if (Py_VerboseFlag && prefix && prefix[0] != '\0')
+            PySys_WriteStderr("# zipimport: prefix=%s constructing a "
+                              "zipimporter for %s\n", prefix, path);
+        /* NOTE(gps): test_zipimport.py never exercises a case where
+         * prefix is non-empty.  When would that ever be possible?
+         * Are we missing coverage or is prefix simply never needed?
+         */
         files = PyDict_GetItemString(zip_directory_cache, path);
         if (files == NULL) {
             PyObject *zip_stat = NULL;
-            FILE *fp = fopen_rb_and_stat(buf, &zip_stat);
+            FILE *fp = fopen_rb_and_stat(path, &zip_stat);
             if (fp == NULL) {
                 PyErr_Format(ZipImportError, "can't open Zip file: "
-                             "'%.200s'", buf);
+                             "'%.200s'", path);
                 Py_XDECREF(zip_stat);
-                return -1;
+                goto error;
             }
 
             if (Py_VerboseFlag)
                 PySys_WriteStderr("# zipimport: %s not cached, "
                                   "reading TOC.\n", path);
 
-            files = read_directory(fp, buf);
+            files = read_directory(fp, path);
             fclose(fp);
             if (files == NULL) {
                 Py_XDECREF(zip_stat);
-                return -1;
+                goto error;
             }
             if (PyDict_SetItemString(zip_directory_cache, path,
                                      files) != 0) {
                 Py_DECREF(files);
                 Py_XDECREF(zip_stat);
-                return -1;
+                goto error;
             }
             if (zip_stat && PyDict_SetItemString(zip_stat_cache, path,
                                                  zip_stat) != 0) {
                 Py_DECREF(files);
                 Py_DECREF(zip_stat);
-                return -1;
+                goto error;
             }
             Py_XDECREF(zip_stat);
         }
-        else
-            Py_INCREF(files);
-        self->files = files;
     }
     else {
         PyErr_SetString(ZipImportError, "not a Zip file");
-        return -1;
+        goto error;
     }
 
     if (prefix == NULL)
@@ -186,33 +194,26 @@
         }
     }
 
-    self->archive = PyString_FromString(buf);
+    self->archive = PyString_FromString(path);
     if (self->archive == NULL)
-        return -1;
+        goto error;
 
     self->prefix = PyString_FromString(prefix);
     if (self->prefix == NULL)
-        return -1;
+        goto error;
 
+    PyMem_Free(path_buf);
     return 0;
-}
-
-/* GC support. */
-static int
-zipimporter_traverse(PyObject *obj, visitproc visit, void *arg)
-{
-    ZipImporter *self = (ZipImporter *)obj;
-    Py_VISIT(self->files);
-    return 0;
+error:
+    PyMem_Free(path_buf);
+    return -1;
 }
 
 static void
 zipimporter_dealloc(ZipImporter *self)
 {
-    PyObject_GC_UnTrack(self);
     Py_XDECREF(self->archive);
     Py_XDECREF(self->prefix);
-    Py_XDECREF(self->files);
     Py_TYPE(self)->tp_free((PyObject *)self);
 }
 
@@ -292,6 +293,7 @@
     char *subname, path[MAXPATHLEN + 1];
     int len;
     struct st_zip_searchorder *zso;
+    PyObject *files;
 
     subname = get_subname(fullname);
 
@@ -299,9 +301,23 @@
     if (len < 0)
         return MI_ERROR;
 
+    files = PyDict_GetItem(zip_directory_cache, self->archive);
+    if (files == NULL) {
+        /* Some scoundrel has cleared zip_directory_cache out from
+         * beneath us.  Try repopulating it once before giving up. */
+        char *unused_archive_name;
+        FILE *fp = safely_reopen_archive(self, &unused_archive_name);
+        if (fp == NULL)
+            return MI_ERROR;
+        fclose(fp);
+        files = PyDict_GetItem(zip_directory_cache, self->archive);
+        if (files == NULL)
+            return MI_ERROR;
+    }
+
     for (zso = zip_searchorder; *zso->suffix; zso++) {
         strcpy(path + len, zso->suffix);
-        if (PyDict_GetItemString(self->files, path) != NULL) {
+        if (PyDict_GetItemString(files, path) != NULL) {
             if (zso->type & IS_PACKAGE)
                 return MI_PACKAGE;
             else
@@ -456,7 +472,7 @@
 #ifdef ALTSEP
     char *p, buf[MAXPATHLEN + 1];
 #endif
-    PyObject *toc_entry, *data;
+    PyObject *toc_entry, *data, *files;
     Py_ssize_t len;
 
     if (!PyArg_ParseTuple(args, "s:zipimporter.get_data", &path))
@@ -485,7 +501,13 @@
     if (fp == NULL)
         return NULL;
 
-    toc_entry = PyDict_GetItemString(self->files, path);
+    files = PyDict_GetItem(zip_directory_cache, self->archive);
+    if (files == NULL) {
+        /* This should never happen as safely_reopen_archive() should
+         * have repopulated zip_directory_cache if needed. */
+        return NULL;
+    }
+    toc_entry = PyDict_GetItemString(files, path);
     if (toc_entry == NULL) {
         PyErr_SetFromErrnoWithFilename(PyExc_IOError, path);
         fclose(fp);
@@ -512,7 +534,7 @@
 zipimporter_get_source(PyObject *obj, PyObject *args)
 {
     ZipImporter *self = (ZipImporter *)obj;
-    PyObject *toc_entry;
+    PyObject *toc_entry, *files;
     FILE *fp;
     char *fullname, *subname, path[MAXPATHLEN+1], *archive;
     int len;
@@ -546,7 +568,13 @@
     if (fp == NULL)
         return NULL;
 
-    toc_entry = PyDict_GetItemString(self->files, path);
+    files = PyDict_GetItem(zip_directory_cache, self->archive);
+    if (files == NULL) {
+        /* This should never happen as safely_reopen_archive() should
+         * have repopulated zip_directory_cache if needed. */
+        return NULL;
+    }
+    toc_entry = PyDict_GetItemString(files, path);
     if (toc_entry != NULL) {
         PyObject *data = get_data(fp, archive, toc_entry);
         fclose(fp);
@@ -666,10 +694,9 @@
     PyObject_GenericGetAttr,                    /* tp_getattro */
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE |
-        Py_TPFLAGS_HAVE_GC,                     /* tp_flags */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,   /* tp_flags */
     zipimporter_doc,                            /* tp_doc */
-    zipimporter_traverse,                       /* tp_traverse */
+    0,                                          /* tp_traverse */
     0,                                          /* tp_clear */
     0,                                          /* tp_richcompare */
     0,                                          /* tp_weaklistoffset */
@@ -686,7 +713,7 @@
     (initproc)zipimporter_init,                 /* tp_init */
     PyType_GenericAlloc,                        /* tp_alloc */
     PyType_GenericNew,                          /* tp_new */
-    PyObject_GC_Del,                            /* tp_free */
+    0,                                          /* tp_free */
 };
 
 
@@ -830,11 +857,13 @@
                 fclose(fp);
                 return NULL;
             }
-            Py_XDECREF(self->files);  /* free the old value. */
-            self->files = files;
         }
         Py_DECREF(stat_now);
-    }  /* stat succeeded */
+    } else {
+        if (Py_VerboseFlag)
+            PySys_WriteStderr("# zipimport: os.fstat failed on the "
+                              "open %s file.\n", archive);
+    }
 
     return fp;
 }
@@ -1236,12 +1265,18 @@
 static time_t
 get_mtime_of_source(ZipImporter *self, char *path)
 {
-    PyObject *toc_entry;
+    PyObject *toc_entry, *files;
     time_t mtime = 0;
     Py_ssize_t lastchar = strlen(path) - 1;
     char savechar = path[lastchar];
     path[lastchar] = '\0';  /* strip 'c' or 'o' from *.py[co] */
-    toc_entry = PyDict_GetItemString(self->files, path);
+    files = PyDict_GetItem(zip_directory_cache, self->archive);
+    if (files == NULL) {
+        /* This should never happen as safely_reopen_archive() from
+         * our only caller repopulated zip_directory_cache if needed. */
+        return 0;
+    }
+    toc_entry = PyDict_GetItemString(files, path);
     if (toc_entry != NULL && PyTuple_Check(toc_entry) &&
         PyTuple_Size(toc_entry) == 8) {
         /* fetch the time stamp of the .py file for comparison
@@ -1304,7 +1339,7 @@
         return NULL;
 
     for (zso = zip_searchorder; *zso->suffix; zso++) {
-        PyObject *code = NULL;
+        PyObject *code = NULL, *files;
 
         strcpy(path + len, zso->suffix);
         if (Py_VerboseFlag > 1)
@@ -1312,7 +1347,14 @@
                               PyString_AsString(self->archive),
                               SEP, path);
 
-        toc_entry = PyDict_GetItemString(self->files, path);
+        files = PyDict_GetItem(zip_directory_cache, self->archive);
+        if (files == NULL) {
+            /* This should never happen as safely_reopen_archive() should
+             * have repopulated zip_directory_cache if needed; and the GIL
+             * is being held. */
+            return NULL;
+        }
+        toc_entry = PyDict_GetItemString(files, path);
         if (toc_entry != NULL) {
             time_t mtime = 0;
             int ispackage = zso->type & IS_PACKAGE;