diff --git a/ANNOUNCE b/ANNOUNCE
index 29b6f0066..5cdabf3a8 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,5 +1,5 @@
 
-Libpng 1.7.0beta17 - July 15, 2013
+Libpng 1.7.0beta17 - August 21, 2013
 
 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.
@@ -22,6 +22,7 @@ Other information:
 
    1.7.0beta17-README.txt
    1.7.0beta17-LICENSE.txt
+   Gnupg/*.asc (PGP armored detached signatures)
 
 Changes since the last public release (1.6.0):
 
@@ -343,10 +344,12 @@ Version 1.7.0beta16 [July 5, 2013]
   Ported ARM no-read patch from libpng16.
   Ported pngfix.c patches from libpng16.
 
-Version 1.7.0beta17 [July 15, 2013]
+Version 1.7.0beta17 [August 21, 2013]
   Revised manual about changes in iTXt chunk handling made in libpng-1.6.0.
   Added "/* SAFE */" comments in pngrutil.c and pngrtran.c where warnings
     may be erroneously issued by code-checking applications.
+  Delay calling png_init_filter_functions() until a row with nonzero filter
+    is found.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/CHANGES b/CHANGES
index 3b59c2a94..a317ecab6 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4633,10 +4633,12 @@ Version 1.7.0beta16 [July 5, 2013]
   Ported ARM no-read patch from libpng16.
   Ported pngfix.c patches from libpng16.
 
-Version 1.7.0beta17 [July 15, 2013]
+Version 1.7.0beta17 [August 21, 2013]
   Revised manual about changes in iTXt chunk handling made in libpng-1.6.0.
   Added "/* SAFE */" comments in pngrutil.c and pngrtran.c where warnings
     may be erroneously issued by code-checking applications.
+  Delay calling png_init_filter_functions() until a row with nonzero filter
+    is found.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/pngrutil.c b/pngrutil.c
index 44bdc4618..c37f91bfa 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -3882,10 +3882,13 @@ png_read_filter_row(png_structrp pp, png_row_infop row_info, png_bytep row,
     * PNG_FILTER_OPTIMIZATIONS to a function that overrides the generic
     * implementations.  See png_init_filter_functions above.
     */
-   if (pp->read_filter[0] == NULL)
-      png_init_filter_functions(pp);
    if (filter > PNG_FILTER_VALUE_NONE && filter < PNG_FILTER_VALUE_LAST)
+   {
+      if (pp->read_filter[0] == NULL)
+         png_init_filter_functions(pp);
+
       pp->read_filter[filter-1](row_info, row, prev_row);
+   }
 }
 
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED