diff --git a/contrib/libtests/gentests.sh b/contrib/libtests/gentests.sh
old mode 100644
new mode 100755
diff --git a/contrib/libtests/pngstest.c b/contrib/libtests/pngstest.c
index 5bb2701a722f442cc2c640bd3adbee203695e654..dc9afce7c9ac03f028f37244081d2fe4101b4fb2 100644
--- a/contrib/libtests/pngstest.c
+++ b/contrib/libtests/pngstest.c
@@ -1973,8 +1973,8 @@ static png_uint_16 gpc_error[16/*in*/][16/*out*/][4/*a*/] =
   { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
   { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
  }, { /* input: color-mapped-sRGB-rgb */
-  { 0, 0, 12, 0 }, { 0, 0, 12, 0 }, { 0, 0, 8, 0 }, { 0, 0, 8, 0 },
-  { 0, 0, 459, 0 }, { 0, 0, 459, 0 }, { 0, 0, 286, 0 }, { 0, 0, 286, 0 },
+  { 0, 0, 13, 0 }, { 0, 0, 13, 0 }, { 0, 0, 8, 0 }, { 0, 0, 8, 0 },
+  { 0, 0, 673, 0 }, { 0, 0, 673, 0 }, { 0, 0, 674, 0 }, { 0, 0, 674, 0 },
   { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
   { 0, 0, 460, 0 }, { 0, 0, 460, 0 }, { 0, 0, 263, 0 }, { 0, 0, 263, 0 }
  }, { /* input: color-mapped-sRGB-rgb+alpha */
@@ -2027,7 +2027,7 @@ static png_uint_16 gpc_error_via_linear[16][4/*out*/][4] =
  }, { /* input: color-mapped-sRGB-gray+alpha */
   { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
  }, { /* input: color-mapped-sRGB-rgb */
-  { 0, 0, 12, 0 }, { 0, 0, 12, 0 }, { 0, 0, 1, 0 }, { 0, 0, 1, 0 }
+  { 0, 0, 13, 0 }, { 0, 0, 13, 0 }, { 0, 0, 14, 0 }, { 0, 0, 14, 0 }
  }, { /* input: color-mapped-sRGB-rgb+alpha */
   { 0, 4, 8, 0 }, { 0, 9, 8, 0 }, { 0, 8, 3, 0 }, { 0, 32, 3, 0 }
  }, { /* input: color-mapped-linear-gray */