diff --git a/ANNOUNCE b/ANNOUNCE
index 5722f7907..b539ef6e9 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,4 +1,4 @@
-Libpng 1.6.29beta01 - January 6, 2017
+Libpng 1.6.29beta01 - January 12, 2017
 
 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.
@@ -25,11 +25,12 @@ Other information:
 
 Changes since the last public release (1.6.28):
 
-Version 1.6.29beta01 [January 6, 2017]
+Version 1.6.29beta01 [January 12, 2017]
   Readded "include(GNUInstallDirs)" to CMakeLists.txt (Gianfranco Costamagna).
   Moved SSE2 optimization code into the main libpng source directory.
     Configure libpng with "configure --enable-intel-sse" or compile
     libpng with "-DPNG_INTEL_SSE" in CPPFLAGS to enable it.
+  Simplified conditional compilation in pngvalid.c, for AIX (Michael Felt).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/CHANGES b/CHANGES
index 789adb9e8..d64e1e868 100644
--- a/CHANGES
+++ b/CHANGES
@@ -5794,11 +5794,12 @@ Version 1.6.28rc03 [January 4, 2017]
 Version 1.6.28 [January 5, 2017]
   No changes.
 
-Version 1.6.29beta01 [January 6, 2017]
+Version 1.6.29beta01 [January 12, 2017]
   Readded "include(GNUInstallDirs)" to CMakeLists.txt (Gianfranco Costamagna).
   Moved SSE2 optimization code into the main libpng source directory.
     Configure libpng with "configure --enable-intel-sse" or compile
     libpng with "-DPNG_INTEL_SSE" in CPPFLAGS to enable it.
+  Simplified conditional compilation in pngvalid.c, for AIX (Michael Felt).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/contrib/libtests/pngvalid.c b/contrib/libtests/pngvalid.c
index 499801b30..fc6031646 100644
--- a/contrib/libtests/pngvalid.c
+++ b/contrib/libtests/pngvalid.c
@@ -7742,13 +7742,11 @@ image_transform_png_set_rgb_to_gray_ini(const image_transform *this,
           * NOTE: this number only affects the internal limit check in pngvalid,
           * it has no effect on the limits applied to the libpng values.
           */
-         that->pm->limit += pow(
-#        if DIGITIZE
-            2.0
-#        else
-            1.0
-#        endif
-            /255, data.gamma);
+#if DIGITIZE
+          that->pm->limit += pow( 2.0/255, data.gamma);
+#else
+          that->pm->limit += pow( 1.0/255, data.gamma);
+#endif
       }
    }