diff --git a/Lib/gettext.py b/Lib/gettext.py
--- a/Lib/gettext.py
+++ b/Lib/gettext.py
@@ -48,7 +48,7 @@
 
 import locale, copy, io, os, re, struct, sys
 from errno import ENOENT
-
+import warnings
 
 __all__ = ['NullTranslations', 'GNUTranslations', 'Catalog',
            'find', 'translation', 'install', 'textdomain', 'bindtextdomain',
@@ -293,7 +293,14 @@
                         self._charset = v.split('charset=')[1]
                     elif k == 'plural-forms':
                         v = v.split(';')
-                        plural = v[1].split('plural=')[1]
+                        if len(v) < 2:
+                            warnings.warn('plural-forms header is empty')
+                            continue
+                        v = v[1].split('plural=')
+                        if len(v) < 2:
+                            warnings.warn('"plural=" not found')
+                            continue
+                        plural = v[1]
                         self.plural = c2py(plural)
             # Note: we unconditionally convert both msgids and msgstrs to
             # Unicode using the character encoding specified in the charset
diff --git a/Lib/test/test_gettext.py b/Lib/test/test_gettext.py
--- a/Lib/test/test_gettext.py
+++ b/Lib/test/test_gettext.py
@@ -81,6 +81,12 @@
 ciBUQUgKdHJnZ3JrZyB6cmZmbnRyIHBuZ255YnQgeXZvZW5lbC4AYmFjb24Ad2luayB3aW5rAA==
 '''
 
+GNU_MO_DATA_ISSUE_12425 = b'''\
+3hIElQAAAAABAAAAHAAAACQAAAAAAAAAAAAAAAAAAAAsAAAAeQAAAC0AAAAAUGx1cmFsLUZvcm1z
+OiBucGx1cmFscz0yOyBwbHVyYWw7CiMtIy0jLSMtIyAgbWVzc2FnZXMucG8gKEVkWCBTdHVkaW8p
+ICAjLSMtIy0jLSMKQ29udGVudC1UeXBlOiB0ZXh0L3BsYWluOyBjaGFyc2V0PVVURi04CgA=
+'''
+
 GNU_MO_DATA_ISSUE_17898 = b'''\
 3hIElQAAAAABAAAAHAAAACQAAAAAAAAAAAAAAAAAAAAsAAAAggAAAC0AAAAAUGx1cmFsLUZvcm1z
 OiBucGx1cmFscz0yOyBwbHVyYWw9KG4gIT0gMSk7CiMtIy0jLSMtIyAgbWVzc2FnZXMucG8gKEVk
@@ -367,6 +373,14 @@
         raises(ValueError, gettext.c2py, "os.chmod('/etc/passwd',0777)")
 
 class GNUTranslationParsingTest(GettextBaseTest):
+    def test_plural_form_warning_issue12425(self):
+        with open(MOFILE, 'wb') as fp:
+            fp.write(base64.decodebytes(GNU_MO_DATA_ISSUE_12425))
+        with open(MOFILE, 'rb') as fp:
+            # If this runs cleanly and issues a warning, the bug is fixed.
+            with self.assertWarns(Warning):
+                t = gettext.GNUTranslations(fp)
+
     def test_plural_form_error_issue17898(self):
         with open(MOFILE, 'wb') as fp:
             fp.write(base64.decodebytes(GNU_MO_DATA_ISSUE_17898))
@@ -562,3 +576,16 @@
 "#-#-#-#-#  messages.po (EdX Studio)  #-#-#-#-#\n"
 "Content-Type: text/plain; charset=UTF-8\n"
 '''
+
+#
+# messages.po, used for bug 12425
+#
+
+'''
+# test file for http://bugs.python.org/issue12425
+msgid ""
+msgstr ""
+"Plural-Forms: nplurals=2; plural;\n"
+"#-#-#-#-#  messages.po (EdX Studio)  #-#-#-#-#\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+'''