diff --git a/ANNOUNCE b/ANNOUNCE
index a66f964..13620f7 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -33,6 +33,12 @@
     grayscale palette builder out of the png?tran.c files. The latter
     isn't a transform function and is no longer used internally, and the
     former MNG specific functions are better placed in pngread/pngwrite.c
+  Made transform implementation functions static. This makes the internal
+    functions called by png_do_{read|write}_transformations static. On an
+    x86-64 DLL build (Gentoo Linux) this reduces the size of the text
+    segment of the DLL by 1208 bytes, about 0.6%. It also simplifies
+    maintenance by removing the declarations from pngpriv.h and allowing
+    easier changes to the internal interfaces.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
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diff --git a/CHANGES b/CHANGES
index d4c2572..a6ae9ae 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4757,6 +4757,12 @@
     grayscale palette builder out of the png?tran.c files. The latter
     isn't a transform function and is no longer used internally, and the
     former MNG specific functions are better placed in pngread/pngwrite.c
+  Made transform implementation functions static. This makes the internal
+    functions called by png_do_{read|write}_transformations static. On an
+    x86-64 DLL build (Gentoo Linux) this reduces the size of the text
+    segment of the DLL by 1208 bytes, about 0.6%. It also simplifies
+    maintenance by removing the declarations from pngpriv.h and allowing
+    easier changes to the internal interfaces.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/pngpriv.h b/pngpriv.h
index e16f501..afa9ed1 100644
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -1235,32 +1235,7 @@
     png_inforp info_ptr),PNG_EMPTY);
 #endif
 
-/* These are the functions that do the transformations */
-#ifdef PNG_READ_FILLER_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_read_filler,(png_row_infop row_info,
-    png_bytep row, png_uint_32 filler, png_uint_32 flags),PNG_EMPTY);
-#endif
-
-#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_read_swap_alpha,(png_row_infop row_info,
-    png_bytep row),PNG_EMPTY);
-#endif
-
-#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_write_swap_alpha,(png_row_infop row_info,
-    png_bytep row),PNG_EMPTY);
-#endif
-
-#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_read_invert_alpha,(png_row_infop row_info,
-    png_bytep row),PNG_EMPTY);
-#endif
-
-#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_write_invert_alpha,(png_row_infop row_info,
-    png_bytep row),PNG_EMPTY);
-#endif
-
+/* Shared transform functions, defined in pngtran.c */
 #if defined(PNG_WRITE_FILLER_SUPPORTED) || \
     defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
 PNG_INTERNAL_FUNCTION(void,png_do_strip_channel,(png_row_infop row_info,
@@ -1280,96 +1255,16 @@
     png_bytep row),PNG_EMPTY);
 #endif
 
-#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
-PNG_INTERNAL_FUNCTION(int,png_do_rgb_to_gray,(png_structrp png_ptr,
-    png_row_infop row_info, png_bytep row),PNG_EMPTY);
-#endif
-
-#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_gray_to_rgb,(png_row_infop row_info,
-    png_bytep row),PNG_EMPTY);
-#endif
-
-#ifdef PNG_READ_PACK_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_unpack,(png_row_infop row_info,
-    png_bytep row),PNG_EMPTY);
-#endif
-
-#ifdef PNG_READ_SHIFT_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_unshift,(png_row_infop row_info,
-    png_bytep row, png_const_color_8p sig_bits),PNG_EMPTY);
-#endif
-
 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
 PNG_INTERNAL_FUNCTION(void,png_do_invert,(png_row_infop row_info,
     png_bytep row),PNG_EMPTY);
 #endif
 
-#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_scale_16_to_8,(png_row_infop row_info,
-    png_bytep row),PNG_EMPTY);
-#endif
-
-#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_chop,(png_row_infop row_info,
-    png_bytep row),PNG_EMPTY);
-#endif
-
-#ifdef PNG_READ_QUANTIZE_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_quantize,(png_row_infop row_info,
-    png_bytep row, png_const_bytep palette_lookup,
-    png_const_bytep quantize_lookup),PNG_EMPTY);
-
-#  ifdef PNG_CORRECT_PALETTE_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_correct_palette,(png_structrp png_ptr,
-    png_colorp palette, int num_palette),PNG_EMPTY);
-#  endif
-#endif
-
 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
 PNG_INTERNAL_FUNCTION(void,png_do_bgr,(png_row_infop row_info,
     png_bytep row),PNG_EMPTY);
 #endif
 
-#ifdef PNG_WRITE_PACK_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_pack,(png_row_infop row_info,
-   png_bytep row, png_uint_32 bit_depth),PNG_EMPTY);
-#endif
-
-#ifdef PNG_WRITE_SHIFT_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_shift,(png_row_infop row_info,
-    png_bytep row, png_const_color_8p bit_depth),PNG_EMPTY);
-#endif
-
-#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
-    defined(PNG_READ_ALPHA_MODE_SUPPORTED)
-PNG_INTERNAL_FUNCTION(void,png_do_compose,(png_row_infop row_info,
-    png_bytep row, png_structrp png_ptr),PNG_EMPTY);
-#endif
-
-#ifdef PNG_READ_GAMMA_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_gamma,(png_row_infop row_info,
-    png_bytep row, png_structrp png_ptr),PNG_EMPTY);
-#endif
-
-#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_encode_alpha,(png_row_infop row_info,
-   png_bytep row, png_structrp png_ptr),PNG_EMPTY);
-#endif
-
-#ifdef PNG_READ_EXPAND_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_expand_palette,(png_row_infop row_info,
-    png_bytep row, png_const_colorp palette, png_const_bytep trans,
-    int num_trans),PNG_EMPTY);
-PNG_INTERNAL_FUNCTION(void,png_do_expand,(png_row_infop row_info,
-    png_bytep row, png_const_color_16p trans_color),PNG_EMPTY);
-#endif
-
-#ifdef PNG_READ_EXPAND_16_SUPPORTED
-PNG_INTERNAL_FUNCTION(void,png_do_expand_16,(png_row_infop row_info,
-    png_bytep row),PNG_EMPTY);
-#endif
-
 /* The following decodes the appropriate chunks, and does error correction,
  * then calls the appropriate callback for the chunk if it is valid.
  */
diff --git a/pngrtran.c b/pngrtran.c
index b2d0b2e..350eaad 100644
--- a/pngrtran.c
+++ b/pngrtran.c
@@ -2130,7 +2130,7 @@
  * the numbers 0 or 1.  If you would rather they contain 0 and 255, use
  * png_do_shift() after this.
  */
-void /* PRIVATE */
+static void
 png_do_unpack(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_unpack");
@@ -2228,7 +2228,7 @@
  * a row of bit depth 8, but only 5 are significant, this will shift
  * the values back to 0 through 31.
  */
-void /* PRIVATE */
+static void
 png_do_unshift(png_row_infop row_info, png_bytep row,
     png_const_color_8p sig_bits)
 {
@@ -2367,7 +2367,7 @@
 
 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
 /* Scale rows of bit depth 16 down to 8 accurately */
-void /* PRIVATE */
+static void
 png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_scale_16_to_8");
@@ -2425,7 +2425,7 @@
 #endif
 
 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
-void /* PRIVATE */
+static void
 /* Simply discard the low byte.  This was the default behavior prior
  * to libpng-1.5.4.
  */
@@ -2453,7 +2453,7 @@
 #endif
 
 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
-void /* PRIVATE */
+static void
 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_read_swap_alpha");
@@ -2550,7 +2550,7 @@
 #endif
 
 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
-void /* PRIVATE */
+static void
 png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
 {
    png_uint_32 row_width;
@@ -2652,7 +2652,7 @@
 
 #ifdef PNG_READ_FILLER_SUPPORTED
 /* Add filler channel if we have RGB color */
-void /* PRIVATE */
+static void
 png_do_read_filler(png_row_infop row_info, png_bytep row,
     png_uint_32 filler, png_uint_32 flags)
 {
@@ -2839,7 +2839,7 @@
 
 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
 /* Expand grayscale files to RGB, with or without alpha */
-void /* PRIVATE */
+static void
 png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
 {
    png_uint_32 i;
@@ -2978,7 +2978,7 @@
  *  calculated to make the sum 32768.  This will result in different rounding
  *  to that used above.
  */
-int /* PRIVATE */
+static int
 png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row)
 
 {
@@ -3179,7 +3179,7 @@
  * "background" is already in the screen gamma, while "background_1" is
  * at a gamma of 1.0.  Paletted files have already been taken care of.
  */
-void /* PRIVATE */
+static void
 png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
 {
 #ifdef PNG_READ_GAMMA_SUPPORTED
@@ -3919,7 +3919,7 @@
  * is 16, use gamma_16_table and gamma_shift.  Build these with
  * build_gamma_table().
  */
-void /* PRIVATE */
+static void
 png_do_gamma(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
 {
    png_const_bytep gamma_table = png_ptr->gamma_table;
@@ -4120,7 +4120,7 @@
  * linear.)  Called only with color types that have an alpha channel.  Needs the
  * from_1 tables.
  */
-void /* PRIVATE */
+static void
 png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
 {
    png_uint_32 row_width = row_info->width;
@@ -4186,7 +4186,7 @@
 /* Expands a palette row to an RGB or RGBA row depending
  * upon whether you supply trans and num_trans.
  */
-void /* PRIVATE */
+static void
 png_do_expand_palette(png_row_infop row_info, png_bytep row,
    png_const_colorp palette, png_const_bytep trans_alpha, int num_trans)
 {
@@ -4339,7 +4339,7 @@
 /* If the bit depth < 8, it is expanded to 8.  Also, if the already
  * expanded transparency value is supplied, an alpha channel is built.
  */
-void /* PRIVATE */
+static void
 png_do_expand(png_row_infop row_info, png_bytep row,
     png_const_color_16p trans_color)
 {
@@ -4569,7 +4569,7 @@
 /* If the bit depth is 8 and the color type is not a palette type expand the
  * whole row to 16 bits.  Has no effect otherwise.
  */
-void /* PRIVATE */
+static void
 png_do_expand_16(png_row_infop row_info, png_bytep row)
 {
    if (row_info->bit_depth == 8 &&
@@ -4597,7 +4597,7 @@
 #endif
 
 #ifdef PNG_READ_QUANTIZE_SUPPORTED
-void /* PRIVATE */
+static void
 png_do_quantize(png_row_infop row_info, png_bytep row,
     png_const_bytep palette_lookup, png_const_bytep quantize_lookup)
 {
diff --git a/pngwtran.c b/pngwtran.c
index 523f244..210a415 100644
--- a/pngwtran.c
+++ b/pngwtran.c
@@ -21,7 +21,7 @@
  * row_info bit depth should be 8 (one pixel per byte).  The channels
  * should be 1 (this only happens on grayscale and paletted images).
  */
-void /* PRIVATE */
+static void
 png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
 {
    png_debug(1, "in png_do_pack");
@@ -166,7 +166,7 @@
  * would pass 3 as bit_depth, and this routine would translate the
  * data to 0 to 15.
  */
-void /* PRIVATE */
+static void
 png_do_shift(png_row_infop row_info, png_bytep row,
     png_const_color_8p bit_depth)
 {
@@ -305,7 +305,7 @@
 #endif
 
 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
-void /* PRIVATE */
+static void
 png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_write_swap_alpha");
@@ -399,7 +399,7 @@
 #endif
 
 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
-void /* PRIVATE */
+static void
 png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
 {
    png_debug(1, "in png_do_write_invert_alpha");