diff --git a/ANNOUNCE b/ANNOUNCE
index a808920d1061415853eb47a6abeb16aca3ac6d34..56d06229183db7fd38f2f967c198e415a11e791b 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -54,6 +54,8 @@ version 1.2.37beta01 [May 14, 2009]
 version 1.2.37beta02 [May 16, 2009]
   Fixed typo in libpng documentation (FILTER_AVE should be FILTER_AVG)
   Relocated misplaced #endif in pngwrite.c, sCAL chunk handler.
+  In pngpread.c and pngrutil.c, set png_ptr->old_prev_row_size=0 to
+    force the prev_row array to be cleared before row 0 of each pass.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 
diff --git a/CHANGES b/CHANGES
index 7a8b7338a781ec6a3517a4a982ceb8d612449a61..c3c02f304b64f9b6b558ed623c4f2ab5d14ea1f3 100644
--- a/CHANGES
+++ b/CHANGES
@@ -2379,6 +2379,8 @@ version 1.2.37beta01 [May 14, 2009]
 version 1.2.37beta02 [May 16, 2009]
   Fixed typo in libpng documentation (FILTER_AVE should be FILTER_AVG)
   Relocated misplaced #endif in pngwrite.c, sCAL chunk handler.
+  In pngpread.c and pngrutil.c, set png_ptr->old_prev_row_size=0 to
+    force the prev_row array to be cleared before row 0 of each pass.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/pngpread.c b/pngpread.c
index b06fbadabd13af82612d15f1e598b019b58ac31b..35ef987da34fa92724766c6dcac0149a414d0fc6 100644
--- a/pngpread.c
+++ b/pngpread.c
@@ -1,9 +1,9 @@
 
 /* pngpread.c - read a png file in push mode
  *
- * Last changed in libpng 1.2.32 [September 18, 2008]
+ * Last changed in libpng 1.2.37 [May 16, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
- * Copyright (c) 1998-2008 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  */
@@ -1013,11 +1013,12 @@ png_read_push_finish_row(png_structp png_ptr)
    if (png_ptr->row_number < png_ptr->num_rows)
       return;
 
+   png_ptr->old_prev_row_size = 0; /* Force clearing prev_row */
+
+#ifdef PNG_READ_INTERLACING_SUPPORTED
    if (png_ptr->interlaced)
    {
       png_ptr->row_number = 0;
-      png_memset_check(png_ptr, png_ptr->prev_row, 0,
-         png_ptr->rowbytes + 1);
       do
       {
          png_ptr->pass++;
@@ -1049,6 +1050,7 @@ png_read_push_finish_row(png_structp png_ptr)
 
       } while (png_ptr->iwidth == 0 || png_ptr->num_rows == 0);
    }
+#endif /* PNG_READ_INTERLACING_SUPPORTED */
 }
 
 #if defined(PNG_READ_tEXt_SUPPORTED)
diff --git a/pngrutil.c b/pngrutil.c
index 46204b9629ea20912e23512727f7eabf3ce63430..b7c083ebe9377de9e07495cb19e633d38bbd0393 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -1,7 +1,7 @@
 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.2.37 [May 15, 2009]
+ * Last changed in libpng 1.2.37 [May 16, 2009]
  * For conditions of distribution and use, see copyright notice in png.h
  * Copyright (c) 1998-2009 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -2913,12 +2913,13 @@ png_read_finish_row(png_structp png_ptr)
    if (png_ptr->row_number < png_ptr->num_rows)
       return;
 
+   /* Force prev_row to be cleared. */
+   png_ptr->old_prev_row_size=0;
+
 #ifdef PNG_READ_INTERLACING_SUPPORTED
    if (png_ptr->interlaced)
    {
       png_ptr->row_number = 0;
-      png_memset_check(png_ptr, png_ptr->prev_row, 0,
-         png_ptr->rowbytes + 1);
       do
       {
          png_ptr->pass++;
@@ -3187,7 +3188,7 @@ defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    if (row_bytes + 64 > png_ptr->old_big_row_buf_size)
    {
      png_free(png_ptr, png_ptr->big_row_buf);
-      png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 64);
+     png_ptr->big_row_buf = (png_bytep)png_malloc(png_ptr, row_bytes + 64);
      if (png_ptr->interlaced)
        png_memset(png_ptr->big_row_buf, 0, row_bytes + 64);
      png_ptr->row_buf = png_ptr->big_row_buf + 32;