diff --git a/PIL/PngImagePlugin.py b/PIL/PngImagePlugin.py
index 7ed018878..9e84e11af 100644
--- a/PIL/PngImagePlugin.py
+++ b/PIL/PngImagePlugin.py
@@ -305,18 +305,28 @@ class PngStream(ChunkStream):
 
         # compressed text
         s = ImageFile._safe_read(self.fp, len)
-        k, v = s.split(b"\0", 1)
-        comp_method = i8(v[0])
+        try:
+            k, v = s.split(b"\0", 1)
+        except ValueError:
+            k = s; v = b""
+        if v:
+            comp_method = i8(v[0])
+        else:
+            comp_method = 0
         if comp_method != 0:
             raise SyntaxError("Unknown compression method %s in zTXt chunk" % comp_method)
         import zlib
-        v = zlib.decompress(v[1:])
+        try:
+            v = zlib.decompress(v[1:])
+        except zlib.error:
+            v = b""
 
-        if bytes is not str:
-            k = k.decode('latin-1', 'strict')
-            v = v.decode('latin-1', 'replace')
+        if k:
+            if bytes is not str:
+                k = k.decode('latin-1', 'strict')
+                v = v.decode('latin-1', 'replace')
 
-        self.im_info[k] = self.im_text[k] = v
+            self.im_info[k] = self.im_text[k] = v
         return s
 
 # --------------------------------------------------------------------
diff --git a/Tests/test_file_png.py b/Tests/test_file_png.py
index 4c14c9a64..067ea5812 100644
--- a/Tests/test_file_png.py
+++ b/Tests/test_file_png.py
@@ -2,6 +2,7 @@ from tester import *
 
 from PIL import Image
 from PIL import PngImagePlugin
+import zlib
 
 codecs = dir(Image.core)
 
@@ -99,6 +100,27 @@ def test_bad_text():
     im = load(HEAD + chunk(b'tEXt', b'spam\0egg\0') + TAIL)
     assert_equal(im.info,  {'spam': 'egg\x00'})
 
+def test_bad_ztxt():
+    # Test reading malformed zTXt chunks (python-imaging/Pillow#318)
+
+    im = load(HEAD + chunk(b'zTXt') + TAIL)
+    assert_equal(im.info, {})
+
+    im = load(HEAD + chunk(b'zTXt', b'spam') + TAIL)
+    assert_equal(im.info, {'spam': ''})
+
+    im = load(HEAD + chunk(b'zTXt', b'spam\0') + TAIL)
+    assert_equal(im.info, {'spam': ''})
+
+    im = load(HEAD + chunk(b'zTXt', b'spam\0\0') + TAIL)
+    assert_equal(im.info, {'spam': ''})
+
+    im = load(HEAD + chunk(b'zTXt', b'spam\0\0' + zlib.compress(b'egg')[:1]) + TAIL)
+    assert_equal(im.info, {'spam': ''})
+
+    im = load(HEAD + chunk(b'zTXt', b'spam\0\0' + zlib.compress(b'egg')) + TAIL)
+    assert_equal(im.info,  {'spam': 'egg'})
+
 def test_interlace():
 
     file = "Tests/images/pil123p.png"