diff --git a/CHANGES.rst b/CHANGES.rst
index 8b48ac1a8..c17b5fdb3 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -5,6 +5,9 @@ Changelog (Pillow)
 7.1.0 (unreleased)
 ------------------
 
+- Only draw each polygon pixel once #4333
+  [radarhere]
+
 - Add support for shooting situation Exif IFD tags #4398
   [alexagv]
 
diff --git a/README.rst b/README.rst
index 253dc89a5..f02268df5 100644
--- a/README.rst
+++ b/README.rst
@@ -61,15 +61,19 @@ To report a security vulnerability, please follow the procedure described in the
    :alt: AppVeyor CI build status (Windows)
 
 .. |gha_lint| image:: https://github.com/python-pillow/Pillow/workflows/Lint/badge.svg
+   :target: https://github.com/python-pillow/Pillow/actions?query=workflow%3ALint
    :alt: GitHub Actions build status (Lint)
 
 .. |gha_docker| image:: https://github.com/python-pillow/Pillow/workflows/Test%20Docker/badge.svg
+   :target: https://github.com/python-pillow/Pillow/actions?query=workflow%3A%22Test+Docker%22
    :alt: GitHub Actions build status (Test Docker)
 
 .. |gha| image:: https://github.com/python-pillow/Pillow/workflows/Test/badge.svg
+   :target: https://github.com/python-pillow/Pillow/actions?query=workflow%3ATest
    :alt: GitHub Actions build status (Test Linux and macOS)
 
 .. |gha_windows| image:: https://github.com/python-pillow/Pillow/workflows/Test%20Windows/badge.svg
+   :target: https://github.com/python-pillow/Pillow/actions?query=workflow%3A%22Test+Windows%22
    :alt: GitHub Actions build status (Test Windows)
 
 .. |coverage| image:: https://codecov.io/gh/python-pillow/Pillow/branch/master/graph/badge.svg
diff --git a/RELEASING.md b/RELEASING.md
index 9614b133f..3a285662c 100644
--- a/RELEASING.md
+++ b/RELEASING.md
@@ -2,7 +2,7 @@
 
 ## Main Release
 
-Released quarterly on the first day of January, April, July, October.
+Released quarterly on January 2nd, April 1st, July 1st and October 15th.
 
 * [ ] Open a release ticket e.g. https://github.com/python-pillow/Pillow/issues/3154
 * [ ] Develop and prepare release in `master` branch.
diff --git a/Tests/helper.py b/Tests/helper.py
index e4b1d917c..3b2341012 100644
--- a/Tests/helper.py
+++ b/Tests/helper.py
@@ -4,6 +4,7 @@ Helper functions.
 
 import logging
 import os
+import shutil
 import subprocess
 import sys
 import tempfile
@@ -191,9 +192,12 @@ class PillowTestCase(unittest.TestCase):
             raise OSError()
 
         outfile = self.tempfile("temp.png")
-        if command_succeeds([IMCONVERT, f, outfile]):
-            return Image.open(outfile)
-        raise OSError()
+        rc = subprocess.call(
+            [IMCONVERT, f, outfile], stdout=subprocess.DEVNULL, stderr=subprocess.STDOUT
+        )
+        if rc:
+            raise OSError
+        return Image.open(outfile)
 
 
 @unittest.skipIf(sys.platform.startswith("win32"), "requires Unix or macOS")
@@ -268,34 +272,20 @@ def hopper(mode=None, cache={}):
     return im.copy()
 
 
-def command_succeeds(cmd):
-    """
-    Runs the command, which must be a list of strings. Returns True if the
-    command succeeds, or False if an OSError was raised by subprocess.Popen.
-    """
-    try:
-        subprocess.call(cmd, stdout=subprocess.DEVNULL, stderr=subprocess.STDOUT)
-    except OSError:
-        return False
-    return True
-
-
 def djpeg_available():
-    return command_succeeds(["djpeg", "-version"])
+    return bool(shutil.which("djpeg"))
 
 
 def cjpeg_available():
-    return command_succeeds(["cjpeg", "-version"])
+    return bool(shutil.which("cjpeg"))
 
 
 def netpbm_available():
-    return command_succeeds(["ppmquant", "--version"]) and command_succeeds(
-        ["ppmtogif", "--version"]
-    )
+    return bool(shutil.which("ppmquant") and shutil.which("ppmtogif"))
 
 
 def imagemagick_available():
-    return IMCONVERT and command_succeeds([IMCONVERT, "-version"])
+    return bool(IMCONVERT and shutil.which(IMCONVERT))
 
 
 def on_appveyor():
diff --git a/Tests/images/imagedraw_chord_zero_width.png b/Tests/images/imagedraw_chord_zero_width.png
new file mode 100644
index 000000000..c1c0058d7
Binary files /dev/null and b/Tests/images/imagedraw_chord_zero_width.png differ
diff --git a/Tests/images/imagedraw_ellipse_translucent.png b/Tests/images/imagedraw_ellipse_translucent.png
new file mode 100644
index 000000000..964dce678
Binary files /dev/null and b/Tests/images/imagedraw_ellipse_translucent.png differ
diff --git a/Tests/images/imagedraw_ellipse_zero_width.png b/Tests/images/imagedraw_ellipse_zero_width.png
new file mode 100644
index 000000000..f14a279f2
Binary files /dev/null and b/Tests/images/imagedraw_ellipse_zero_width.png differ
diff --git a/Tests/images/imagedraw_pieslice_zero_width.png b/Tests/images/imagedraw_pieslice_zero_width.png
new file mode 100644
index 000000000..4ca051583
Binary files /dev/null and b/Tests/images/imagedraw_pieslice_zero_width.png differ
diff --git a/Tests/images/imagedraw_rectangle_zero_width.png b/Tests/images/imagedraw_rectangle_zero_width.png
new file mode 100644
index 000000000..989c95761
Binary files /dev/null and b/Tests/images/imagedraw_rectangle_zero_width.png differ
diff --git a/Tests/test_file_container.py b/Tests/test_file_container.py
index 91166b39e..b752e217f 100644
--- a/Tests/test_file_container.py
+++ b/Tests/test_file_container.py
@@ -20,7 +20,7 @@ def test_isatty():
 def test_seek_mode_0():
     # Arrange
     mode = 0
-    with open(TEST_FILE) as fh:
+    with open(TEST_FILE, "rb") as fh:
         container = ContainerIO.ContainerIO(fh, 22, 100)
 
         # Act
@@ -34,7 +34,7 @@ def test_seek_mode_0():
 def test_seek_mode_1():
     # Arrange
     mode = 1
-    with open(TEST_FILE) as fh:
+    with open(TEST_FILE, "rb") as fh:
         container = ContainerIO.ContainerIO(fh, 22, 100)
 
         # Act
@@ -48,7 +48,7 @@ def test_seek_mode_1():
 def test_seek_mode_2():
     # Arrange
     mode = 2
-    with open(TEST_FILE) as fh:
+    with open(TEST_FILE, "rb") as fh:
         container = ContainerIO.ContainerIO(fh, 22, 100)
 
         # Act
@@ -61,73 +61,87 @@ def test_seek_mode_2():
 
 def test_read_n0():
     # Arrange
-    with open(TEST_FILE) as fh:
-        container = ContainerIO.ContainerIO(fh, 22, 100)
+    for bytesmode in (True, False):
+        with open(TEST_FILE, "rb" if bytesmode else "r") as fh:
+            container = ContainerIO.ContainerIO(fh, 22, 100)
 
-        # Act
-        container.seek(81)
-        data = container.read()
+            # Act
+            container.seek(81)
+            data = container.read()
 
-        # Assert
-        assert data == "7\nThis is line 8\n"
+            # Assert
+            if bytesmode:
+                data = data.decode()
+            assert data == "7\nThis is line 8\n"
 
 
 def test_read_n():
     # Arrange
-    with open(TEST_FILE) as fh:
-        container = ContainerIO.ContainerIO(fh, 22, 100)
+    for bytesmode in (True, False):
+        with open(TEST_FILE, "rb" if bytesmode else "r") as fh:
+            container = ContainerIO.ContainerIO(fh, 22, 100)
 
-        # Act
-        container.seek(81)
-        data = container.read(3)
+            # Act
+            container.seek(81)
+            data = container.read(3)
 
-        # Assert
-        assert data == "7\nT"
+            # Assert
+            if bytesmode:
+                data = data.decode()
+            assert data == "7\nT"
 
 
 def test_read_eof():
     # Arrange
-    with open(TEST_FILE) as fh:
-        container = ContainerIO.ContainerIO(fh, 22, 100)
+    for bytesmode in (True, False):
+        with open(TEST_FILE, "rb" if bytesmode else "r") as fh:
+            container = ContainerIO.ContainerIO(fh, 22, 100)
 
-        # Act
-        container.seek(100)
-        data = container.read()
+            # Act
+            container.seek(100)
+            data = container.read()
 
-        # Assert
-        assert data == ""
+            # Assert
+            if bytesmode:
+                data = data.decode()
+            assert data == ""
 
 
 def test_readline():
     # Arrange
-    with open(TEST_FILE) as fh:
-        container = ContainerIO.ContainerIO(fh, 0, 120)
+    for bytesmode in (True, False):
+        with open(TEST_FILE, "rb" if bytesmode else "r") as fh:
+            container = ContainerIO.ContainerIO(fh, 0, 120)
 
-        # Act
-        data = container.readline()
+            # Act
+            data = container.readline()
 
-        # Assert
-        assert data == "This is line 1\n"
+            # Assert
+            if bytesmode:
+                data = data.decode()
+            assert data == "This is line 1\n"
 
 
 def test_readlines():
     # Arrange
-    expected = [
-        "This is line 1\n",
-        "This is line 2\n",
-        "This is line 3\n",
-        "This is line 4\n",
-        "This is line 5\n",
-        "This is line 6\n",
-        "This is line 7\n",
-        "This is line 8\n",
-    ]
-    with open(TEST_FILE) as fh:
-        container = ContainerIO.ContainerIO(fh, 0, 120)
+    for bytesmode in (True, False):
+        expected = [
+            "This is line 1\n",
+            "This is line 2\n",
+            "This is line 3\n",
+            "This is line 4\n",
+            "This is line 5\n",
+            "This is line 6\n",
+            "This is line 7\n",
+            "This is line 8\n",
+        ]
+        with open(TEST_FILE, "rb" if bytesmode else "r") as fh:
+            container = ContainerIO.ContainerIO(fh, 0, 120)
 
-        # Act
-        data = container.readlines()
+            # Act
+            data = container.readlines()
 
-        # Assert
-
-        assert data == expected
+            # Assert
+            if bytesmode:
+                data = [line.decode() for line in data]
+            assert data == expected
diff --git a/Tests/test_imagedraw.py b/Tests/test_imagedraw.py
index e5951fb02..bd8c06560 100644
--- a/Tests/test_imagedraw.py
+++ b/Tests/test_imagedraw.py
@@ -228,6 +228,19 @@ def test_chord_width_fill():
     assert_image_similar(im, Image.open(expected), 1)
 
 
+def test_chord_zero_width():
+    # Arrange
+    im = Image.new("RGB", (W, H))
+    draw = ImageDraw.Draw(im)
+
+    # Act
+    draw.chord(BBOX1, 10, 260, fill="red", outline="yellow", width=0)
+
+    # Assert
+    with Image.open("Tests/images/imagedraw_chord_zero_width.png") as expected:
+        assert_image_equal(im, expected)
+
+
 def helper_ellipse(mode, bbox):
     # Arrange
     im = Image.new(mode, (W, H))
@@ -310,6 +323,19 @@ def test_ellipse_width_fill():
     assert_image_similar(im, Image.open(expected), 1)
 
 
+def test_ellipse_zero_width():
+    # Arrange
+    im = Image.new("RGB", (W, H))
+    draw = ImageDraw.Draw(im)
+
+    # Act
+    draw.ellipse(BBOX1, fill="green", outline="blue", width=0)
+
+    # Assert
+    with Image.open("Tests/images/imagedraw_ellipse_zero_width.png") as expected:
+        assert_image_equal(im, expected)
+
+
 def helper_line(points):
     # Arrange
     im = Image.new("RGB", (W, H))
@@ -420,6 +446,19 @@ def test_pieslice_width_fill():
     assert_image_similar(im, Image.open(expected), 1)
 
 
+def test_pieslice_zero_width():
+    # Arrange
+    im = Image.new("RGB", (W, H))
+    draw = ImageDraw.Draw(im)
+
+    # Act
+    draw.pieslice(BBOX1, 10, 260, fill="white", outline="blue", width=0)
+
+    # Assert
+    with Image.open("Tests/images/imagedraw_pieslice_zero_width.png") as expected:
+        assert_image_equal(im, expected)
+
+
 def helper_point(points):
     # Arrange
     im = Image.new("RGB", (W, H))
@@ -537,6 +576,19 @@ def test_rectangle_width_fill():
     assert_image_equal(im, Image.open(expected))
 
 
+def test_rectangle_zero_width():
+    # Arrange
+    im = Image.new("RGB", (W, H))
+    draw = ImageDraw.Draw(im)
+
+    # Act
+    draw.rectangle(BBOX1, fill="blue", outline="green", width=0)
+
+    # Assert
+    with Image.open("Tests/images/imagedraw_rectangle_zero_width.png") as expected:
+        assert_image_equal(im, expected)
+
+
 def test_rectangle_I16():
     # Arrange
     im = Image.new("I;16", (W, H))
diff --git a/docs/reference/ImageDraw.rst b/docs/reference/ImageDraw.rst
index ad0fe4abe..6700deab4 100644
--- a/docs/reference/ImageDraw.rst
+++ b/docs/reference/ImageDraw.rst
@@ -154,7 +154,7 @@ Methods
     To paste pixel data into an image, use the
     :py:meth:`~PIL.Image.Image.paste` method on the image itself.
 
-.. py:method:: PIL.ImageDraw.ImageDraw.chord(xy, start, end, fill=None, outline=None, width=0)
+.. py:method:: PIL.ImageDraw.ImageDraw.chord(xy, start, end, fill=None, outline=None, width=1)
 
     Same as :py:meth:`~PIL.ImageDraw.ImageDraw.arc`, but connects the end points
     with a straight line.
@@ -168,7 +168,7 @@ Methods
 
         .. versionadded:: 5.3.0
 
-.. py:method:: PIL.ImageDraw.ImageDraw.ellipse(xy, fill=None, outline=None, width=0)
+.. py:method:: PIL.ImageDraw.ImageDraw.ellipse(xy, fill=None, outline=None, width=1)
 
     Draws an ellipse inside the given bounding box.
 
@@ -198,7 +198,7 @@ Methods
 
         .. versionadded:: 5.3.0
 
-.. py:method:: PIL.ImageDraw.ImageDraw.pieslice(xy, start, end, fill=None, outline=None, width=0)
+.. py:method:: PIL.ImageDraw.ImageDraw.pieslice(xy, start, end, fill=None, outline=None, width=1)
 
     Same as arc, but also draws straight lines between the end points and the
     center of the bounding box.
@@ -236,7 +236,7 @@ Methods
     :param outline: Color to use for the outline.
     :param fill: Color to use for the fill.
 
-.. py:method:: PIL.ImageDraw.ImageDraw.rectangle(xy, fill=None, outline=None, width=0)
+.. py:method:: PIL.ImageDraw.ImageDraw.rectangle(xy, fill=None, outline=None, width=1)
 
     Draws a rectangle.
 
diff --git a/src/PIL/ContainerIO.py b/src/PIL/ContainerIO.py
index 9727601ab..5bb0086f6 100644
--- a/src/PIL/ContainerIO.py
+++ b/src/PIL/ContainerIO.py
@@ -82,7 +82,7 @@ class ContainerIO:
         else:
             n = self.length - self.pos
         if not n:  # EOF
-            return ""
+            return b"" if "b" in self.fh.mode else ""
         self.pos = self.pos + n
         return self.fh.read(n)
 
@@ -92,13 +92,14 @@ class ContainerIO:
 
         :returns: An 8-bit string.
         """
-        s = ""
+        s = b"" if "b" in self.fh.mode else ""
+        newline_character = b"\n" if "b" in self.fh.mode else "\n"
         while True:
             c = self.read(1)
             if not c:
                 break
             s = s + c
-            if c == "\n":
+            if c == newline_character:
                 break
         return s
 
diff --git a/src/PIL/ImageDraw.py b/src/PIL/ImageDraw.py
index c6e12150e..7abd459f9 100644
--- a/src/PIL/ImageDraw.py
+++ b/src/PIL/ImageDraw.py
@@ -134,20 +134,20 @@ class ImageDraw:
         if ink is not None:
             self.draw.draw_bitmap(xy, bitmap.im, ink)
 
-    def chord(self, xy, start, end, fill=None, outline=None, width=0):
+    def chord(self, xy, start, end, fill=None, outline=None, width=1):
         """Draw a chord."""
         ink, fill = self._getink(outline, fill)
         if fill is not None:
             self.draw.draw_chord(xy, start, end, fill, 1)
-        if ink is not None and ink != fill:
+        if ink is not None and ink != fill and width != 0:
             self.draw.draw_chord(xy, start, end, ink, 0, width)
 
-    def ellipse(self, xy, fill=None, outline=None, width=0):
+    def ellipse(self, xy, fill=None, outline=None, width=1):
         """Draw an ellipse."""
         ink, fill = self._getink(outline, fill)
         if fill is not None:
             self.draw.draw_ellipse(xy, fill, 1)
-        if ink is not None and ink != fill:
+        if ink is not None and ink != fill and width != 0:
             self.draw.draw_ellipse(xy, ink, 0, width)
 
     def line(self, xy, fill=None, width=0, joint=None):
@@ -219,12 +219,12 @@ class ImageDraw:
         if ink is not None and ink != fill:
             self.draw.draw_outline(shape, ink, 0)
 
-    def pieslice(self, xy, start, end, fill=None, outline=None, width=0):
+    def pieslice(self, xy, start, end, fill=None, outline=None, width=1):
         """Draw a pieslice."""
         ink, fill = self._getink(outline, fill)
         if fill is not None:
             self.draw.draw_pieslice(xy, start, end, fill, 1)
-        if ink is not None and ink != fill:
+        if ink is not None and ink != fill and width != 0:
             self.draw.draw_pieslice(xy, start, end, ink, 0, width)
 
     def point(self, xy, fill=None):
@@ -241,12 +241,12 @@ class ImageDraw:
         if ink is not None and ink != fill:
             self.draw.draw_polygon(xy, ink, 0)
 
-    def rectangle(self, xy, fill=None, outline=None, width=0):
+    def rectangle(self, xy, fill=None, outline=None, width=1):
         """Draw a rectangle."""
         ink, fill = self._getink(outline, fill)
         if fill is not None:
             self.draw.draw_rectangle(xy, fill, 1)
-        if ink is not None and ink != fill:
+        if ink is not None and ink != fill and width != 0:
             self.draw.draw_rectangle(xy, ink, 0, width)
 
     def _multiline_check(self, text):
diff --git a/src/libImaging/Draw.c b/src/libImaging/Draw.c
index c1f7684ea..58adc1b63 100644
--- a/src/libImaging/Draw.c
+++ b/src/libImaging/Draw.c
@@ -415,6 +415,35 @@ x_cmp(const void *x0, const void *x1)
 }
 
 
+static void
+draw_horizontal_lines(Imaging im, int n, Edge *e, int ink, int *x_pos, int y, hline_handler hline)
+{
+    int i;
+    for (i = 0; i < n; i++) {
+        if (e[i].ymin == y && e[i].ymin == e[i].ymax) {
+            int xmax;
+            int xmin = e[i].xmin;
+            if (*x_pos < xmin) {
+                // Line would be after the current position
+                continue;
+            }
+
+            xmax = e[i].xmax;
+            if (*x_pos > xmin) {
+                // Line would be partway through x_pos, so increase the starting point
+                xmin = *x_pos;
+                if (xmax < xmin) {
+                    // Line would now end before it started
+                    continue;
+                }
+            }
+
+            (*hline)(im, xmin, e[i].ymin, xmax, ink);
+            *x_pos = xmax+1;
+        }
+    }
+}
+
 /*
  * Filled polygon draw function using scan line algorithm.
  */
@@ -442,10 +471,7 @@ polygon_generic(Imaging im, int n, Edge *e, int ink, int eofill,
     }
 
     for (i = 0; i < n; i++) {
-        /* This causes the pixels of horizontal edges to be drawn twice :(
-         * but without it there are inconsistencies in ellipses */
         if (e[i].ymin == e[i].ymax) {
-            (*hline)(im, e[i].xmin, e[i].ymin, e[i].xmax, ink);
             continue;
         }
         if (ymin > e[i].ymin) {
@@ -472,6 +498,7 @@ polygon_generic(Imaging im, int n, Edge *e, int ink, int eofill,
     }
     for (; ymin <= ymax; ymin++) {
         int j = 0;
+        int x_pos = 0;
         for (i = 0; i < edge_count; i++) {
             Edge* current = edge_table[i];
             if (ymin >= current->ymin && ymin <= current->ymax) {
@@ -485,8 +512,30 @@ polygon_generic(Imaging im, int n, Edge *e, int ink, int eofill,
         }
         qsort(xx, j, sizeof(float), x_cmp);
         for (i = 1; i < j; i += 2) {
-            (*hline)(im, ROUND_UP(xx[i - 1]), ymin, ROUND_DOWN(xx[i]), ink);
+            int x_end = ROUND_DOWN(xx[i]);
+            if (x_end < x_pos) {
+                // Line would be before the current position
+                continue;
+            }
+            draw_horizontal_lines(im, n, e, ink, &x_pos, ymin, hline);
+            if (x_end < x_pos) {
+                // Line would be before the current position
+                continue;
+            }
+
+            int x_start = ROUND_UP(xx[i-1]);
+            if (x_pos > x_start) {
+                // Line would be partway through x_pos, so increase the starting point
+                x_start = x_pos;
+                if (x_end < x_start) {
+                    // Line would now end before it started
+                    continue;
+                }
+            }
+            (*hline)(im, x_start, ymin, x_end, ink);
+            x_pos = x_end+1;
         }
+        draw_horizontal_lines(im, n, e, ink, &x_pos, ymin, hline);
     }
 
     free(xx);
diff --git a/src/libImaging/QuantHeap.c b/src/libImaging/QuantHeap.c
index 121b87275..498d44b1d 100644
--- a/src/libImaging/QuantHeap.c
+++ b/src/libImaging/QuantHeap.c
@@ -26,8 +26,8 @@
 
 struct _Heap {
    void **heap;
-   int heapsize;
-   int heapcount;
+   unsigned int heapsize;
+   unsigned int heapcount;
    HeapCmpFunc cf;
 };
 
@@ -44,7 +44,7 @@ void ImagingQuantHeapFree(Heap *h) {
    free(h);
 }
 
-static int _heap_grow(Heap *h,int newsize) {
+static int _heap_grow(Heap *h,unsigned int newsize) {
    void *newheap;
    if (!newsize) newsize=h->heapsize<<1;
    if (newsize<h->heapsize) return 0;
@@ -64,7 +64,7 @@ static int _heap_grow(Heap *h,int newsize) {
 
 #ifdef DEBUG
 static int _heap_test(Heap *h) {
-   int k;
+   unsigned int k;
    for (k=1;k*2<=h->heapcount;k++) {
       if (h->cf(h,h->heap[k],h->heap[k*2])<0) {
          printf ("heap is bad\n");
@@ -80,7 +80,7 @@ static int _heap_test(Heap *h) {
 #endif
 
 int ImagingQuantHeapRemove(Heap* h,void **r) {
-   int k,l;
+   unsigned int k,l;
    void *v;
 
    if (!h->heapcount) {
diff --git a/src/libImaging/QuantOctree.c b/src/libImaging/QuantOctree.c
index 6c0f605c9..83d987544 100644
--- a/src/libImaging/QuantOctree.c
+++ b/src/libImaging/QuantOctree.c
@@ -44,7 +44,7 @@ typedef struct _ColorCube{
    unsigned int rWidth, gWidth, bWidth, aWidth;
    unsigned int rOffset, gOffset, bOffset, aOffset;
 
-   long size;
+   unsigned long size;
    ColorBucket buckets;
 } *ColorCube;
 
@@ -134,10 +134,10 @@ add_color_to_color_cube(const ColorCube cube, const Pixel *p) {
    bucket->a += p->c.a;
 }
 
-static long
+static unsigned long
 count_used_color_buckets(const ColorCube cube) {
-   long usedBuckets = 0;
-   long i;
+   unsigned long usedBuckets = 0;
+   unsigned long i;
    for (i=0; i < cube->size; i++) {
       if (cube->buckets[i].count > 0) {
          usedBuckets += 1;
@@ -194,7 +194,7 @@ void add_bucket_values(ColorBucket src, ColorBucket dst) {
 
 /* expand or shrink a given cube to level */
 static ColorCube copy_color_cube(const ColorCube cube,
-   int rBits, int gBits, int bBits, int aBits)
+   unsigned int rBits, unsigned int gBits, unsigned int bBits, unsigned int aBits)
 {
    unsigned int r, g, b, a;
    long src_pos, dst_pos;
@@ -302,7 +302,7 @@ void add_lookup_buckets(ColorCube cube, ColorBucket palette, long nColors, long
 }
 
 ColorBucket
-combined_palette(ColorBucket bucketsA, long nBucketsA, ColorBucket bucketsB, long nBucketsB) {
+combined_palette(ColorBucket bucketsA, unsigned long nBucketsA, ColorBucket bucketsB, unsigned long nBucketsB) {
    ColorBucket result;
    if (nBucketsA > LONG_MAX - nBucketsB ||
        (nBucketsA+nBucketsB) > LONG_MAX / sizeof(struct _ColorBucket)) {
@@ -345,8 +345,8 @@ map_image_pixels(const Pixel *pixelData,
    }
 }
 
-const int CUBE_LEVELS[8]       = {4, 4, 4, 0, 2, 2, 2, 0};
-const int CUBE_LEVELS_ALPHA[8] = {3, 4, 3, 3, 2, 2, 2, 2};
+const unsigned int CUBE_LEVELS[8]       = {4, 4, 4, 0, 2, 2, 2, 0};
+const unsigned int CUBE_LEVELS_ALPHA[8] = {3, 4, 3, 3, 2, 2, 2, 2};
 
 int quantize_octree(Pixel *pixelData,
           uint32_t nPixels,
@@ -365,8 +365,8 @@ int quantize_octree(Pixel *pixelData,
    ColorBucket paletteBuckets = NULL;
    uint32_t *qp = NULL;
    long i;
-   long nCoarseColors, nFineColors, nAlreadySubtracted;
-   const int *cubeBits;
+   unsigned long nCoarseColors, nFineColors, nAlreadySubtracted;
+   const unsigned int *cubeBits;
 
    if (withAlpha) {
        cubeBits = CUBE_LEVELS_ALPHA;