diff --git a/docs/releasenotes/11.0.0.rst b/docs/releasenotes/11.0.0.rst
index 0175ae52d..1d1afcde5 100644
--- a/docs/releasenotes/11.0.0.rst
+++ b/docs/releasenotes/11.0.0.rst
@@ -85,3 +85,10 @@ others prepare for 3.13, and to ensure Pillow could be used immediately at the r
 of 3.13.0 final (2024-10-01, :pep:`719`).
 
 Pillow 11.0.0 now officially supports Python 3.13.
+
+C-level Flags
+^^^^^^^^^^^^^
+
+Some compiling flags like ``WITH_THREADING``, ``WITH_IMAGECHOPS``, and other
+``WITH_*`` were removed. These flags were not available through the build system,
+but they could be edited in the C source.
diff --git a/src/_imaging.c b/src/_imaging.c
index a2606df15..07d9a64cc 100644
--- a/src/_imaging.c
+++ b/src/_imaging.c
@@ -94,19 +94,6 @@
 #include <math.h>
 #include <stddef.h>
 
-/* Configuration stuff. Feel free to undef things you don't need. */
-#define WITH_IMAGECHOPS  /* ImageChops support */
-#define WITH_IMAGEDRAW   /* ImageDraw support */
-#define WITH_MAPPING     /* use memory mapping to read some file formats */
-#define WITH_IMAGEPATH   /* ImagePath stuff */
-#define WITH_ARROW       /* arrow graphics stuff (experimental) */
-#define WITH_EFFECTS     /* special effects */
-#define WITH_QUANTIZE    /* quantization support */
-#define WITH_RANKFILTER  /* rank filter */
-#define WITH_MODEFILTER  /* mode filter */
-#define WITH_THREADING   /* "friendly" threading support */
-#define WITH_UNSHARPMASK /* Kevin Cazabon's unsharpmask module */
-
 #undef VERBOSE
 
 #define B16(p, i) ((((int)p[(i)]) << 8) + p[(i) + 1])
@@ -124,8 +111,6 @@ typedef struct {
 
 static PyTypeObject Imaging_Type;
 
-#ifdef WITH_IMAGEDRAW
-
 typedef struct {
     /* to write a character, cut out sxy from glyph data, place
        at current position plus dxy, and advance by (dx, dy) */
@@ -152,8 +137,6 @@ typedef struct {
 
 static PyTypeObject ImagingDraw_Type;
 
-#endif
-
 typedef struct {
     PyObject_HEAD ImagingObject *image;
     int readonly;
@@ -216,16 +199,12 @@ PyImaging_AsImaging(PyObject *op) {
 
 void
 ImagingSectionEnter(ImagingSectionCookie *cookie) {
-#ifdef WITH_THREADING
     *cookie = (PyThreadState *)PyEval_SaveThread();
-#endif
 }
 
 void
 ImagingSectionLeave(ImagingSectionCookie *cookie) {
-#ifdef WITH_THREADING
     PyEval_RestoreThread((PyThreadState *)*cookie);
-#endif
 }
 
 /* -------------------------------------------------------------------- */
@@ -1092,7 +1071,6 @@ _filter(ImagingObject *self, PyObject *args) {
     return imOut;
 }
 
-#ifdef WITH_UNSHARPMASK
 static PyObject *
 _gaussian_blur(ImagingObject *self, PyObject *args) {
     Imaging imIn;
@@ -1117,7 +1095,6 @@ _gaussian_blur(ImagingObject *self, PyObject *args) {
 
     return PyImagingNew(imOut);
 }
-#endif
 
 static PyObject *
 _getpalette(ImagingObject *self, PyObject *args) {
@@ -1375,7 +1352,6 @@ _entropy(ImagingObject *self, PyObject *args) {
     return PyFloat_FromDouble(-entropy);
 }
 
-#ifdef WITH_MODEFILTER
 static PyObject *
 _modefilter(ImagingObject *self, PyObject *args) {
     int size;
@@ -1385,7 +1361,6 @@ _modefilter(ImagingObject *self, PyObject *args) {
 
     return PyImagingNew(ImagingModeFilter(self->image, size));
 }
-#endif
 
 static PyObject *
 _offset(ImagingObject *self, PyObject *args) {
@@ -1717,8 +1692,6 @@ _putdata(ImagingObject *self, PyObject *args) {
     return Py_None;
 }
 
-#ifdef WITH_QUANTIZE
-
 static PyObject *
 _quantize(ImagingObject *self, PyObject *args) {
     int colours = 256;
@@ -1735,7 +1708,6 @@ _quantize(ImagingObject *self, PyObject *args) {
 
     return PyImagingNew(ImagingQuantize(self->image, colours, method, kmeans));
 }
-#endif
 
 static PyObject *
 _putpalette(ImagingObject *self, PyObject *args) {
@@ -1871,7 +1843,6 @@ _putpixel(ImagingObject *self, PyObject *args) {
     return Py_None;
 }
 
-#ifdef WITH_RANKFILTER
 static PyObject *
 _rankfilter(ImagingObject *self, PyObject *args) {
     int size, rank;
@@ -1881,7 +1852,6 @@ _rankfilter(ImagingObject *self, PyObject *args) {
 
     return PyImagingNew(ImagingRankFilter(self->image, size, rank));
 }
-#endif
 
 static PyObject *
 _resize(ImagingObject *self, PyObject *args) {
@@ -2163,7 +2133,6 @@ _transpose(ImagingObject *self, PyObject *args) {
     return PyImagingNew(imOut);
 }
 
-#ifdef WITH_UNSHARPMASK
 static PyObject *
 _unsharp_mask(ImagingObject *self, PyObject *args) {
     Imaging imIn;
@@ -2187,7 +2156,6 @@ _unsharp_mask(ImagingObject *self, PyObject *args) {
 
     return PyImagingNew(imOut);
 }
-#endif
 
 static PyObject *
 _box_blur(ImagingObject *self, PyObject *args) {
@@ -2464,9 +2432,7 @@ _split(ImagingObject *self) {
     return list;
 }
 
-/* -------------------------------------------------------------------- */
-
-#ifdef WITH_IMAGECHOPS
+/* Channel operations (ImageChops) ------------------------------------ */
 
 static PyObject *
 _chop_invert(ImagingObject *self) {
@@ -2647,11 +2613,8 @@ _chop_overlay(ImagingObject *self, PyObject *args) {
 
     return PyImagingNew(ImagingOverlay(self->image, imagep->image));
 }
-#endif
 
-/* -------------------------------------------------------------------- */
-
-#ifdef WITH_IMAGEDRAW
+/* Fonts (ImageDraw and ImageFont) ------------------------------------ */
 
 static PyObject *
 _font_new(PyObject *self_, PyObject *args) {
@@ -2880,7 +2843,7 @@ static struct PyMethodDef _font_methods[] = {
     {NULL, NULL} /* sentinel */
 };
 
-/* -------------------------------------------------------------------- */
+/* Graphics (ImageDraw) ----------------------------------------------- */
 
 static PyObject *
 _draw_new(PyObject *self_, PyObject *args) {
@@ -3234,8 +3197,6 @@ _draw_points(ImagingDrawObject *self, PyObject *args) {
     return Py_None;
 }
 
-#ifdef WITH_ARROW
-
 /* from outline.c */
 extern ImagingOutline
 PyOutline_AsOutline(PyObject *outline);
@@ -3265,8 +3226,6 @@ _draw_outline(ImagingDrawObject *self, PyObject *args) {
     return Py_None;
 }
 
-#endif
-
 static PyObject *
 _draw_pieslice(ImagingDrawObject *self, PyObject *args) {
     double *xy;
@@ -3432,12 +3391,9 @@ _draw_rectangle(ImagingDrawObject *self, PyObject *args) {
 }
 
 static struct PyMethodDef _draw_methods[] = {
-#ifdef WITH_IMAGEDRAW
     /* Graphics (ImageDraw) */
     {"draw_lines", (PyCFunction)_draw_lines, METH_VARARGS},
-#ifdef WITH_ARROW
     {"draw_outline", (PyCFunction)_draw_outline, METH_VARARGS},
-#endif
     {"draw_polygon", (PyCFunction)_draw_polygon, METH_VARARGS},
     {"draw_rectangle", (PyCFunction)_draw_rectangle, METH_VARARGS},
     {"draw_points", (PyCFunction)_draw_points, METH_VARARGS},
@@ -3447,12 +3403,9 @@ static struct PyMethodDef _draw_methods[] = {
     {"draw_ellipse", (PyCFunction)_draw_ellipse, METH_VARARGS},
     {"draw_pieslice", (PyCFunction)_draw_pieslice, METH_VARARGS},
     {"draw_ink", (PyCFunction)_draw_ink, METH_VARARGS},
-#endif
     {NULL, NULL} /* sentinel */
 };
 
-#endif
-
 static PyObject *
 pixel_access_new(ImagingObject *imagep, PyObject *args) {
     PixelAccessObject *self;
@@ -3533,11 +3486,9 @@ pixel_access_setitem(PixelAccessObject *self, PyObject *xy, PyObject *color) {
 }
 
 /* -------------------------------------------------------------------- */
-/* EFFECTS (experimental)                            */
+/* EFFECTS (experimental)                                               */
 /* -------------------------------------------------------------------- */
 
-#ifdef WITH_EFFECTS
-
 static PyObject *
 _effect_mandelbrot(ImagingObject *self, PyObject *args) {
     int xsize = 512;
@@ -3589,8 +3540,6 @@ _effect_spread(ImagingObject *self, PyObject *args) {
     return PyImagingNew(ImagingEffectSpread(self->image, dist));
 }
 
-#endif
-
 /* -------------------------------------------------------------------- */
 /* UTILITIES                                */
 /* -------------------------------------------------------------------- */
@@ -3671,20 +3620,14 @@ static struct PyMethodDef methods[] = {
     {"filter", (PyCFunction)_filter, METH_VARARGS},
     {"histogram", (PyCFunction)_histogram, METH_VARARGS},
     {"entropy", (PyCFunction)_entropy, METH_VARARGS},
-#ifdef WITH_MODEFILTER
     {"modefilter", (PyCFunction)_modefilter, METH_VARARGS},
-#endif
     {"offset", (PyCFunction)_offset, METH_VARARGS},
     {"paste", (PyCFunction)_paste, METH_VARARGS},
     {"point", (PyCFunction)_point, METH_VARARGS},
     {"point_transform", (PyCFunction)_point_transform, METH_VARARGS},
     {"putdata", (PyCFunction)_putdata, METH_VARARGS},
-#ifdef WITH_QUANTIZE
     {"quantize", (PyCFunction)_quantize, METH_VARARGS},
-#endif
-#ifdef WITH_RANKFILTER
     {"rankfilter", (PyCFunction)_rankfilter, METH_VARARGS},
-#endif
     {"resize", (PyCFunction)_resize, METH_VARARGS},
     {"reduce", (PyCFunction)_reduce, METH_VARARGS},
     {"transpose", (PyCFunction)_transpose, METH_VARARGS},
@@ -3710,7 +3653,6 @@ static struct PyMethodDef methods[] = {
     {"putpalettealpha", (PyCFunction)_putpalettealpha, METH_VARARGS},
     {"putpalettealphas", (PyCFunction)_putpalettealphas, METH_VARARGS},
 
-#ifdef WITH_IMAGECHOPS
     /* Channel operations (ImageChops) */
     {"chop_invert", (PyCFunction)_chop_invert, METH_NOARGS},
     {"chop_lighter", (PyCFunction)_chop_lighter, METH_VARARGS},
@@ -3729,20 +3671,14 @@ static struct PyMethodDef methods[] = {
     {"chop_hard_light", (PyCFunction)_chop_hard_light, METH_VARARGS},
     {"chop_overlay", (PyCFunction)_chop_overlay, METH_VARARGS},
 
-#endif
-
-#ifdef WITH_UNSHARPMASK
-    /* Kevin Cazabon's unsharpmask extension */
+    /* Unsharpmask extension */
     {"gaussian_blur", (PyCFunction)_gaussian_blur, METH_VARARGS},
     {"unsharp_mask", (PyCFunction)_unsharp_mask, METH_VARARGS},
-#endif
 
     {"box_blur", (PyCFunction)_box_blur, METH_VARARGS},
 
-#ifdef WITH_EFFECTS
     /* Special effects */
     {"effect_spread", (PyCFunction)_effect_spread, METH_VARARGS},
-#endif
 
     /* Misc. */
     {"new_block", (PyCFunction)_new_block, METH_VARARGS},
@@ -3871,8 +3807,6 @@ static PyTypeObject Imaging_Type = {
     getsetters,           /*tp_getset*/
 };
 
-#ifdef WITH_IMAGEDRAW
-
 static PyTypeObject ImagingFont_Type = {
     PyVarObject_HEAD_INIT(NULL, 0) "ImagingFont", /*tp_name*/
     sizeof(ImagingFontObject),                    /*tp_basicsize*/
@@ -3939,8 +3873,6 @@ static PyTypeObject ImagingDraw_Type = {
     0,                         /*tp_getset*/
 };
 
-#endif
-
 static PyMappingMethods pixel_access_as_mapping = {
     (lenfunc)NULL,                       /*mp_length*/
     (binaryfunc)pixel_access_getitem,    /*mp_subscript*/
@@ -4309,13 +4241,11 @@ static PyMethodDef functions[] = {
     {"zip_encoder", (PyCFunction)PyImaging_ZipEncoderNew, METH_VARARGS},
 #endif
 
-/* Memory mapping */
-#ifdef WITH_MAPPING
+    /* Memory mapping */
     {"map_buffer", (PyCFunction)PyImaging_MapBuffer, METH_VARARGS},
-#endif
 
-/* Display support */
 #ifdef _WIN32
+    /* Display support */
     {"display", (PyCFunction)PyImaging_DisplayWin32, METH_VARARGS},
     {"display_mode", (PyCFunction)PyImaging_DisplayModeWin32, METH_VARARGS},
     {"grabscreen_win32", (PyCFunction)PyImaging_GrabScreenWin32, METH_VARARGS},
@@ -4331,30 +4261,22 @@ static PyMethodDef functions[] = {
     /* Utilities */
     {"getcodecstatus", (PyCFunction)_getcodecstatus, METH_VARARGS},
 
-/* Special effects (experimental) */
-#ifdef WITH_EFFECTS
+    /* Special effects (experimental) */
     {"effect_mandelbrot", (PyCFunction)_effect_mandelbrot, METH_VARARGS},
     {"effect_noise", (PyCFunction)_effect_noise, METH_VARARGS},
     {"linear_gradient", (PyCFunction)_linear_gradient, METH_VARARGS},
     {"radial_gradient", (PyCFunction)_radial_gradient, METH_VARARGS},
     {"wedge", (PyCFunction)_linear_gradient, METH_VARARGS}, /* Compatibility */
-#endif
 
-/* Drawing support stuff */
-#ifdef WITH_IMAGEDRAW
+    /* Drawing support stuff */
     {"font", (PyCFunction)_font_new, METH_VARARGS},
     {"draw", (PyCFunction)_draw_new, METH_VARARGS},
-#endif
 
-/* Experimental path stuff */
-#ifdef WITH_IMAGEPATH
+    /* Experimental path stuff */
     {"path", (PyCFunction)PyPath_Create, METH_VARARGS},
-#endif
 
-/* Experimental arrow graphics stuff */
-#ifdef WITH_ARROW
+    /* Experimental arrow graphics stuff */
     {"outline", (PyCFunction)PyOutline_Create, METH_VARARGS},
-#endif
 
     /* Resource management */
     {"get_stats", (PyCFunction)_get_stats, METH_VARARGS},
@@ -4379,16 +4301,12 @@ setup_module(PyObject *m) {
     if (PyType_Ready(&Imaging_Type) < 0) {
         return -1;
     }
-
-#ifdef WITH_IMAGEDRAW
     if (PyType_Ready(&ImagingFont_Type) < 0) {
         return -1;
     }
-
     if (PyType_Ready(&ImagingDraw_Type) < 0) {
         return -1;
     }
-#endif
     if (PyType_Ready(&PixelAccess_Type) < 0) {
         return -1;
     }
diff --git a/src/libImaging/Pack.c b/src/libImaging/Pack.c
index f3b714215..c29473d90 100644
--- a/src/libImaging/Pack.c
+++ b/src/libImaging/Pack.c
@@ -258,16 +258,6 @@ void
 ImagingPackRGB(UINT8 *out, const UINT8 *in, int pixels) {
     int i = 0;
     /* RGB triplets */
-#ifdef __sparc
-    /* SPARC CPUs cannot read integers from nonaligned addresses. */
-    for (; i < pixels; i++) {
-        out[0] = in[R];
-        out[1] = in[G];
-        out[2] = in[B];
-        out += 3;
-        in += 4;
-    }
-#else
     for (; i < pixels - 1; i++) {
         memcpy(out, in + i * 4, 4);
         out += 3;
@@ -278,7 +268,6 @@ ImagingPackRGB(UINT8 *out, const UINT8 *in, int pixels) {
         out[2] = in[i * 4 + B];
         out += 3;
     }
-#endif
 }
 
 void
diff --git a/src/libImaging/Quant.c b/src/libImaging/Quant.c
index 197f9f3ee..595ee42a0 100644
--- a/src/libImaging/Quant.c
+++ b/src/libImaging/Quant.c
@@ -36,7 +36,8 @@
 #define UINT32_MAX 0xffffffff
 #endif
 
-#define NO_OUTPUT
+// #define DEBUG
+// #define TEST_NEAREST_NEIGHBOUR
 
 typedef struct {
     uint32_t scale;
@@ -144,7 +145,7 @@ create_pixel_hash(Pixel *pixelData, uint32_t nPixels) {
     PixelHashData *d;
     HashTable *hash;
     uint32_t i;
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     uint32_t timer, timer2, timer3;
 #endif
 
@@ -156,7 +157,7 @@ create_pixel_hash(Pixel *pixelData, uint32_t nPixels) {
     hash = hashtable_new(pixel_hash, pixel_cmp);
     hashtable_set_user_data(hash, d);
     d->scale = 0;
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     timer = timer3 = clock();
 #endif
     for (i = 0; i < nPixels; i++) {
@@ -167,22 +168,22 @@ create_pixel_hash(Pixel *pixelData, uint32_t nPixels) {
         }
         while (hashtable_get_count(hash) > MAX_HASH_ENTRIES) {
             d->scale++;
-#ifndef NO_OUTPUT
+#ifdef DEBUG
             printf("rehashing - new scale: %d\n", (int)d->scale);
             timer2 = clock();
 #endif
             hashtable_rehash_compute(hash, rehash_collide);
-#ifndef NO_OUTPUT
+#ifdef DEBUG
             timer2 = clock() - timer2;
             printf("rehash took %f sec\n", timer2 / (double)CLOCKS_PER_SEC);
             timer += timer2;
 #endif
         }
     }
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("inserts took %f sec\n", (clock() - timer) / (double)CLOCKS_PER_SEC);
 #endif
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("total        %f sec\n", (clock() - timer3) / (double)CLOCKS_PER_SEC);
 #endif
     return hash;
@@ -304,7 +305,7 @@ mergesort_pixels(PixelList *head, int i) {
     return head;
 }
 
-#if defined(TEST_MERGESORT) || defined(TEST_SORTED)
+#ifdef DEBUG
 static int
 test_sorted(PixelList *pl[3]) {
     int i, n, l;
@@ -347,12 +348,12 @@ splitlists(
     PixelList *l, *r, *c, *n;
     int i;
     int nRight;
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     int nLeft;
 #endif
     int splitColourVal;
 
-#ifdef TEST_SPLIT
+#ifdef DEBUG
     {
         PixelList *_prevTest, *_nextTest;
         int _i, _nextCount[3], _prevCount[3];
@@ -402,14 +403,14 @@ splitlists(
 #endif
     nCount[0] = nCount[1] = 0;
     nRight = 0;
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     nLeft = 0;
 #endif
     for (left = 0, c = h[axis]; c;) {
         left = left + c->count;
         nCount[0] += c->count;
         c->flag = 0;
-#ifndef NO_OUTPUT
+#ifdef DEBUG
         nLeft++;
 #endif
         c = c->next[axis];
@@ -424,7 +425,7 @@ splitlists(
                 break;
             }
             c->flag = 0;
-#ifndef NO_OUTPUT
+#ifdef DEBUG
             nLeft++;
 #endif
             nCount[0] += c->count;
@@ -442,14 +443,14 @@ splitlists(
             }
             c->flag = 1;
             nRight++;
-#ifndef NO_OUTPUT
+#ifdef DEBUG
             nLeft--;
 #endif
             nCount[0] -= c->count;
             nCount[1] += c->count;
         }
     }
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     if (!nLeft) {
         for (c = h[axis]; c; c = c->next[axis]) {
             printf("[%d %d %d]\n", c->p.c.r, c->p.c.g, c->p.c.b);
@@ -511,7 +512,7 @@ split(BoxNode *node) {
     gl = node->tail[1]->p.c.g;
     bh = node->head[2]->p.c.b;
     bl = node->tail[2]->p.c.b;
-#ifdef TEST_SPLIT
+#ifdef DEBUG
     printf("splitting node [%d %d %d] [%d %d %d] ", rl, gl, bl, rh, gh, bh);
 #endif
     f[0] = (rh - rl) * 77;
@@ -526,11 +527,8 @@ split(BoxNode *node) {
             axis = i;
         }
     }
-#ifdef TEST_SPLIT
+#ifdef DEBUG
     printf("along axis %d\n", axis + 1);
-#endif
-
-#ifdef TEST_SPLIT
     {
         PixelList *_prevTest, *_nextTest;
         int _i, _nextCount[3], _prevCount[3];
@@ -592,12 +590,12 @@ split(BoxNode *node) {
     if (!splitlists(
             node->head, node->tail, heads, tails, newCounts, axis, node->pixelCount
         )) {
-#ifndef NO_OUTPUT
+#ifdef DEBUG
         printf("list split failed.\n");
 #endif
         return 0;
     }
-#ifdef TEST_SPLIT
+#ifdef DEBUG
     if (!test_sorted(heads[0])) {
         printf("bug in split");
         exit(1);
@@ -623,7 +621,7 @@ split(BoxNode *node) {
         node->head[i] = NULL;
         node->tail[i] = NULL;
     }
-#ifdef TEST_SPLIT
+#ifdef DEBUG
     if (left->head[0]) {
         rh = left->head[0]->p.c.r;
         rl = left->tail[0]->p.c.r;
@@ -687,7 +685,7 @@ median_cut(PixelList *hl[3], uint32_t imPixelCount, int nPixels) {
             }
         } while (compute_box_volume(thisNode) == 1);
         if (!split(thisNode)) {
-#ifndef NO_OUTPUT
+#ifdef DEBUG
             printf("Oops, split failed...\n");
 #endif
             exit(1);
@@ -716,16 +714,14 @@ free_box_tree(BoxNode *n) {
     free(n);
 }
 
-#ifdef TEST_SPLIT_INTEGRITY
+#ifdef DEBUG
 static int
 checkContained(BoxNode *n, Pixel *pp) {
     if (n->l && n->r) {
         return checkContained(n->l, pp) + checkContained(n->r, pp);
     }
     if (n->l || n->r) {
-#ifndef NO_OUTPUT
         printf("box tree is dead\n");
-#endif
         return 0;
     }
     if (pp->c.r <= n->head[0]->p.c.r && pp->c.r >= n->tail[0]->p.c.r &&
@@ -746,7 +742,7 @@ annotate_hash_table(BoxNode *n, HashTable *h, uint32_t *box) {
         return annotate_hash_table(n->l, h, box) && annotate_hash_table(n->r, h, box);
     }
     if (n->l || n->r) {
-#ifndef NO_OUTPUT
+#ifdef DEBUG
         printf("box tree is dead\n");
 #endif
         return 0;
@@ -754,7 +750,7 @@ annotate_hash_table(BoxNode *n, HashTable *h, uint32_t *box) {
     for (p = n->head[0]; p; p = p->next[0]) {
         PIXEL_UNSCALE(&(p->p), &q, d->scale);
         if (!hashtable_insert(h, q, *box)) {
-#ifndef NO_OUTPUT
+#ifdef DEBUG
             printf("hashtable insert failed\n");
 #endif
             return 0;
@@ -978,7 +974,7 @@ map_image_pixels_from_median_box(
             continue;
         }
         if (!hashtable_lookup(medianBoxHash, pixelData[i], &pixelVal)) {
-#ifndef NO_OUTPUT
+#ifdef DEBUG
             printf("pixel lookup failed\n");
 #endif
             return 0;
@@ -1043,7 +1039,7 @@ compute_palette_from_median_cut(
         }
     }
     for (i = 0; i < nPixels; i++) {
-#ifdef TEST_SPLIT_INTEGRITY
+#ifdef DEBUG
         if (!(i % 100)) {
             printf("%05d\r", i);
             fflush(stdout);
@@ -1058,7 +1054,7 @@ compute_palette_from_median_cut(
         }
 #endif
         if (!hashtable_lookup(medianBoxHash, pixelData[i], &paletteEntry)) {
-#ifndef NO_OUTPUT
+#ifdef DEBUG
             printf("pixel lookup failed\n");
 #endif
             for (i = 0; i < 3; i++) {
@@ -1068,7 +1064,7 @@ compute_palette_from_median_cut(
             return 0;
         }
         if (paletteEntry >= nPaletteEntries) {
-#ifndef NO_OUTPUT
+#ifdef DEBUG
             printf(
                 "panic - paletteEntry>=nPaletteEntries (%d>=%d)\n",
                 (int)paletteEntry,
@@ -1140,7 +1136,7 @@ compute_palette_from_quantized_pixels(
     }
     for (i = 0; i < nPixels; i++) {
         if (qp[i] >= nPaletteEntries) {
-#ifndef NO_OUTPUT
+#ifdef DEBUG
             printf("scream\n");
 #endif
             return 0;
@@ -1208,7 +1204,7 @@ k_means(
         goto error_2;
     }
 
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("[");
     fflush(stdout);
 #endif
@@ -1243,7 +1239,7 @@ k_means(
         if (changes < 0) {
             goto error_3;
         }
-#ifndef NO_OUTPUT
+#ifdef DEBUG
         printf(".(%d)", changes);
         fflush(stdout);
 #endif
@@ -1251,7 +1247,7 @@ k_means(
             break;
         }
     }
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("]\n");
 #endif
     if (avgDistSortKey) {
@@ -1311,32 +1307,32 @@ quantize(
     uint32_t **avgDistSortKey;
     Pixel *p;
 
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     uint32_t timer, timer2;
 #endif
 
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     timer2 = clock();
     printf("create hash table...");
     fflush(stdout);
     timer = clock();
 #endif
     h = create_pixel_hash(pixelData, nPixels);
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("done (%f)\n", (clock() - timer) / (double)CLOCKS_PER_SEC);
 #endif
     if (!h) {
         goto error_0;
     }
 
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("create lists from hash table...");
     fflush(stdout);
     timer = clock();
 #endif
     hl[0] = hl[1] = hl[2] = NULL;
     hashtable_foreach(h, hash_to_list, hl);
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("done (%f)\n", (clock() - timer) / (double)CLOCKS_PER_SEC);
 #endif
 
@@ -1344,7 +1340,7 @@ quantize(
         goto error_1;
     }
 
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("mergesort lists...");
     fflush(stdout);
     timer = clock();
@@ -1352,39 +1348,37 @@ quantize(
     for (i = 0; i < 3; i++) {
         hl[i] = mergesort_pixels(hl[i], i);
     }
-#ifdef TEST_MERGESORT
+#ifdef DEBUG
     if (!test_sorted(hl)) {
         printf("bug in mergesort\n");
         goto error_1;
     }
-#endif
-#ifndef NO_OUTPUT
     printf("done (%f)\n", (clock() - timer) / (double)CLOCKS_PER_SEC);
 #endif
 
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("median cut...");
     fflush(stdout);
     timer = clock();
 #endif
     root = median_cut(hl, nPixels, nQuantPixels);
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("done (%f)\n", (clock() - timer) / (double)CLOCKS_PER_SEC);
 #endif
     if (!root) {
         goto error_1;
     }
     nPaletteEntries = 0;
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("median cut tree to hash table...");
     fflush(stdout);
     timer = clock();
 #endif
     annotate_hash_table(root, h, &nPaletteEntries);
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("done (%f)\n", (clock() - timer) / (double)CLOCKS_PER_SEC);
 #endif
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("compute palette...\n");
     fflush(stdout);
     timer = clock();
@@ -1392,7 +1386,7 @@ quantize(
     if (!compute_palette_from_median_cut(pixelData, nPixels, h, &p, nPaletteEntries)) {
         goto error_3;
     }
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("done (%f)\n", (clock() - timer) / (double)CLOCKS_PER_SEC);
 #endif
 
@@ -1479,7 +1473,7 @@ quantize(
         hashtable_free(h2);
     }
 #endif
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("k means...\n");
     fflush(stdout);
     timer = clock();
@@ -1487,7 +1481,7 @@ quantize(
     if (kmeans > 0) {
         k_means(pixelData, nPixels, p, nPaletteEntries, qp, kmeans - 1);
     }
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("done (%f)\n", (clock() - timer) / (double)CLOCKS_PER_SEC);
 #endif
 
@@ -1495,7 +1489,7 @@ quantize(
     *palette = p;
     *paletteLength = nPaletteEntries;
 
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("cleanup...");
     fflush(stdout);
     timer = clock();
@@ -1507,7 +1501,7 @@ quantize(
         free(avgDistSortKey);
     }
     destroy_pixel_hash(h);
-#ifndef NO_OUTPUT
+#ifdef DEBUG
     printf("done (%f)\n", (clock() - timer) / (double)CLOCKS_PER_SEC);
     printf("-----\ntotal time %f\n", (clock() - timer2) / (double)CLOCKS_PER_SEC);
 #endif