diff --git a/ANNOUNCE b/ANNOUNCE
index 6ef155d66..b4cfe7e97 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,5 +1,5 @@
 
-Libpng 1.5.22rc04 - March 15, 2015
+Libpng 1.5.22rc04 - March 16, 2015
 
 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -61,9 +61,11 @@ Version 1.5.22rc03 [March 12, 2015]
   Updated CMakeLists.txt to add OSX framework, change YES/NO to ON/OFF
     for consistency, and remove some useless tests (Alexey Petruchik).
 
-Version 1.5.22rc04 [March 15, 2015]
+Version 1.5.22rc04 [March 16, 2015]
   Remove pnglibconf.h, pnglibconf.c, and pnglibconf.out instead of
     pnglibconf.* in "make clean" (Cosmin).
+  Fix incorrect calculation of maximum number of unknown chunks or
+    sPLT chunks to be stored (John Bowler).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/CHANGES b/CHANGES
index 1d4f8ea7b..2694d2334 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4325,9 +4325,11 @@ Version 1.5.22rc03 [March 12, 2015]
   Updated CMakeLists.txt to add OSX framework, change YES/NO to ON/OFF
     for consistency, and remove some useless tests (Alexey Petruchik).
 
-Version 1.5.22rc04 [March 15, 2015]
+Version 1.5.22rc04 [March 16, 2015]
   Remove pnglibconf.h, pnglibconf.c, and pnglibconf.out instead of
     pnglibconf.* in "make clean" (Cosmin).
+  Fix incorrect calculation of maximum number of unknown chunks or
+    sPLT chunks to be stored (John Bowler).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/pngset.c b/pngset.c
index 3efc085ae..3de1dcb0e 100644
--- a/pngset.c
+++ b/pngset.c
@@ -977,7 +977,7 @@ png_set_sPLT(png_structp png_ptr,
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 
-   element_size = PNG_SIZE_MAX/png_sizeof(png_sPLT_t);
+   element_size = png_sizeof(png_sPLT_t);
    if (nentries < 0 ||
        nentries > INT_MAX-info_ptr->splt_palettes_num ||
        (unsigned int)/*SAFE*/(nentries +/*SAFE*/
@@ -1058,7 +1058,7 @@ png_set_unknown_chunks(png_structp png_ptr,
    if (png_ptr == NULL || info_ptr == NULL || num_unknowns == 0)
       return;
 
-   element_size = PNG_SIZE_MAX/png_sizeof(png_unknown_chunk);
+   element_size = png_sizeof(png_unknown_chunk);
    if (num_unknowns < 0 ||
        num_unknowns > INT_MAX-info_ptr->unknown_chunks_num ||
        (unsigned int)/*SAFE*/(num_unknowns +/*SAFE*/