diff --git a/CHANGES.rst b/CHANGES.rst
index d36ca4ce8..6a9712da3 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -13,6 +13,9 @@ Changelog (Pillow)
 - Fixed opening and saving odd sized .pcx files, fixes #523
   [wiredfool]
 
+- Fixed palette handling when converting from mode P->RGB->P
+  [d_schmidt] 
+
 - Fixed saving mode P image as a PNG with transparency = palette color 0
   [d-schmidt]
 
diff --git a/PIL/GifImagePlugin.py b/PIL/GifImagePlugin.py
index aed525824..c6d449425 100644
--- a/PIL/GifImagePlugin.py
+++ b/PIL/GifImagePlugin.py
@@ -237,7 +237,10 @@ def _save(im, fp, filename):
         # convert on the fly (EXPERIMENTAL -- I'm not sure PIL
         # should automatically convert images on save...)
         if Image.getmodebase(im.mode) == "RGB":
-            imOut = im.convert("P")
+            palette_size = 256
+            if im.palette:
+                palette_size = len(im.palette.getdata()[1]) // 3
+            imOut = im.convert("P", palette=1, colors=palette_size)
             rawmode = "P"
         else:
             imOut = im.convert("L")
@@ -248,9 +251,13 @@ def _save(im, fp, filename):
         palette = im.encoderinfo["palette"]
     except KeyError:
         palette = None
-        if im.palette:
-            # use existing if possible
-            palette = im.palette.getdata()[1]
+        im.encoderinfo["optimize"] = im.encoderinfo.get("optimize", True)
+        if im.encoderinfo["optimize"]:
+            # When the mode is L, and we optimize, we end up with
+            # im.mode == P and rawmode = L, which fails.
+            # If we're optimizing the palette, we're going to be
+            # in a rawmode of P anyway. 
+            rawmode = 'P'
 
     header, usedPaletteColors = getheader(imOut, palette, im.encoderinfo)
     for s in header:
@@ -391,6 +398,9 @@ def getheader(im, palette=None, info=None):
             for i in range(len(imageBytes)):
                 imageBytes[i] = newPositions[imageBytes[i]]
             im.frombytes(bytes(imageBytes))
+            newPaletteBytes = paletteBytes + (768 - len(paletteBytes)) * b'\x00'
+            im.putpalette(newPaletteBytes) 
+            im.palette = ImagePalette.ImagePalette("RGB", palette = paletteBytes, size = len(paletteBytes))
 
     if not paletteBytes:
         paletteBytes = sourcePalette
diff --git a/PIL/Image.py b/PIL/Image.py
index 0d8a235eb..75e7efc75 100644
--- a/PIL/Image.py
+++ b/PIL/Image.py
@@ -737,7 +737,10 @@ class Image:
 
         if mode == "P" and palette == ADAPTIVE:
             im = self.im.quantize(colors)
-            return self._new(im)
+            new = self._new(im)
+            from PIL import ImagePalette
+            new.palette = ImagePalette.raw("RGB", new.im.getpalette("RGB"))
+            return new
 
         # colorspace conversion
         if dither is None:
diff --git a/PIL/ImagePalette.py b/PIL/ImagePalette.py
index 61affdb19..d5b9d04eb 100644
--- a/PIL/ImagePalette.py
+++ b/PIL/ImagePalette.py
@@ -23,13 +23,14 @@ from PIL import Image, ImageColor
 class ImagePalette:
     "Color palette for palette mapped images"
 
-    def __init__(self, mode = "RGB", palette = None):
+    def __init__(self, mode = "RGB", palette = None, size = 0):
         self.mode = mode
         self.rawmode = None # if set, palette contains raw data
         self.palette = palette or list(range(256))*len(self.mode)
         self.colors = {}
         self.dirty = None
-        if len(self.mode)*256 != len(self.palette):
+        if ((size == 0 and len(self.mode)*256 != len(self.palette)) or 
+                (size != 0 and size != len(self.palette))):
             raise ValueError("wrong palette size")
 
     def getdata(self):
diff --git a/PIL/PngImagePlugin.py b/PIL/PngImagePlugin.py
index 18abf27d3..2bdf74608 100644
--- a/PIL/PngImagePlugin.py
+++ b/PIL/PngImagePlugin.py
@@ -505,7 +505,7 @@ def _save(im, fp, filename, chunk=putchunk, check=0):
         else:
             # check palette contents
             if im.palette:
-                colors = len(im.palette.getdata()[1])//3
+                colors = max(min(len(im.palette.getdata()[1])//3, 256), 2)
             else:
                 colors = 256
 
diff --git a/Tests/images/test.colors.gif b/Tests/images/test.colors.gif
new file mode 100644
index 000000000..0faf96760
Binary files /dev/null and b/Tests/images/test.colors.gif differ
diff --git a/Tests/test_file_gif.py b/Tests/test_file_gif.py
index 3a6478e2a..4318e178e 100644
--- a/Tests/test_file_gif.py
+++ b/Tests/test_file_gif.py
@@ -38,7 +38,7 @@ def test_roundtrip():
 
 def test_roundtrip2():
     #see https://github.com/python-imaging/Pillow/issues/403
-    out = 'temp.gif'#tempfile('temp.gif')
+    out = tempfile('temp.gif')
     im = Image.open('Images/lena.gif')
     im2 = im.copy()
     im2.save(out)
@@ -46,3 +46,42 @@ def test_roundtrip2():
 
     assert_image_similar(reread.convert('RGB'), lena(), 50)
 
+
+def test_palette_handling():
+    # see https://github.com/python-imaging/Pillow/issues/513
+
+    im = Image.open('Images/lena.gif')
+    im = im.convert('RGB')
+    
+    im = im.resize((100,100), Image.ANTIALIAS)
+    im2 = im.convert('P', palette=Image.ADAPTIVE, colors=256)
+
+    f = tempfile('temp.gif')
+    im2.save(f, optimize=True)
+
+    reloaded = Image.open(f)
+    
+    assert_image_similar(im, reloaded.convert('RGB'), 10)
+    
+def test_palette_434():
+    # see https://github.com/python-imaging/Pillow/issues/434
+
+    def roundtrip(im, *args, **kwargs):
+        out = tempfile('temp.gif')
+        im.save(out, *args, **kwargs)
+        reloaded = Image.open(out)
+
+        return [im, reloaded]
+
+    orig = "Tests/images/test.colors.gif"
+    im = Image.open(orig)
+
+    assert_image_equal(*roundtrip(im))
+    assert_image_equal(*roundtrip(im, optimize=True))
+    
+    im = im.convert("RGB")
+    # check automatic P conversion
+    reloaded = roundtrip(im)[1].convert('RGB')
+    assert_image_equal(im, reloaded)
+
+