diff --git a/ANNOUNCE b/ANNOUNCE
index 77e5f9e..b104735 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,5 +1,5 @@
 
-Libpng 1.7.0beta90 - August 19, 2017
+Libpng 1.7.0beta90 - August 28, 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.
@@ -1439,7 +1439,9 @@
   Check for 0 return from png_get_rowbytes() in contrib/pngminus/*.c to stop
     some Coverity issues (162705, 162706, and 162707).
 
-Version 1.7.0beta90 [August 19, 2017]
+Version 1.7.0beta90 [August 28, 2017]
+  Added PNGMINUS_UNUSED macro to contrib/pngminus/p*.c and added missing
+    parenthesis in contrib/pngminus/pnm2png.c (bug report by Christian Hesse).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/CHANGES b/CHANGES
index 85b19e0..04ca10f 100644
--- a/CHANGES
+++ b/CHANGES
@@ -5740,7 +5740,9 @@
   Check for 0 return from png_get_rowbytes() in contrib/pngminus/*.c to stop
     some Coverity issues (162705, 162706, and 162707).
 
-Version 1.7.0beta90 [August 19, 2017]
+Version 1.7.0beta90 [August 28, 2017]
+  Added PNGMINUS_UNUSED macro to contrib/pngminus/p*.c and added missing
+    parenthesis in contrib/pngminus/pnm2png.c (bug report by Christian Hesse).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/contrib/pngminus/png2pnm.c b/contrib/pngminus/png2pnm.c
index 39a9f46..1420a78 100644
--- a/contrib/pngminus/png2pnm.c
+++ b/contrib/pngminus/png2pnm.c
@@ -5,7 +5,8 @@
  *  version 1.0 - 1999.10.15 - First version.
  *          1.1 - 2017.04.22 - Add buffer-size check (Glenn Randers-Pehrson)
  *          1.2 - 2017.08.24 - Fix potential overflow in buffer-size check
-                               (Glenn Randers-Pehrson)
+ *                             (Glenn Randers-Pehrson)
+ *          1.3 - 2017.08.28 - Add PNGMINUS_UNUSED (Christian Hesse)
  *
  *  Permission to use, copy, modify, and distribute this software and
  *  its documentation for any purpose and without fee is hereby granted,
@@ -44,6 +45,7 @@
 #define PNG_DEBUG 0
 #endif
 
+
 #include "png.h"
 
 /* Define png_jmpbuf() in case we are using a pre-1.0.6 version of libpng */
@@ -51,6 +53,14 @@
 #  define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
 #endif
 
+#ifndef PNGMINUS_UNUSED
+/* Unused formal parameter warnings are silenced using the following macro
+ * which is expected to have no bad effects on performance (optimizing
+ * compilers will probably remove it entirely).
+ */
+#  define PNGMINUS_UNUSED(param) (void)param
+#endif
+
 /* function prototypes */
 
 int  main (int argc, char *argv[]);
@@ -443,7 +453,7 @@
   if (png_pixels != (unsigned char*) NULL)
     free (png_pixels);
 
-  PNG_UNUSED(raw) /* to quiet a Coverity defect */
+  PNGMINUS_UNUSED(raw); /* to quiet a Coverity defect */
   return TRUE;
 
 } /* end of source */
diff --git a/contrib/pngminus/pnm2png.c b/contrib/pngminus/pnm2png.c
index 1b550b8..2298136 100644
--- a/contrib/pngminus/pnm2png.c
+++ b/contrib/pngminus/pnm2png.c
@@ -7,6 +7,7 @@
  *  version 1.2 - 2017.04.22 - Add buffer-size check
  *          1.3 - 2017.08.24 - Fix potential overflow in buffer-size check
  *                             (Glenn Randers-Pehrson)
+ *          1.4 - 2017.08.28 - Add PNGMINUS_UNUSED (Christian Hesse)
  *
  *  Permission to use, copy, modify, and distribute this software and
  *  its documentation for any purpose and without fee is hereby granted,
@@ -50,6 +51,15 @@
 #  define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
 #endif
 
+#ifndef PNGMINUS_UNUSED
+/* Unused formal parameter warnings are silenced using the following macro
+ * which is expected to have no bad effects on performance (optimizing
+ * compilers will probably remove it entirely).
+ */
+#  define PNGMINUS_UNUSED(param) (void)param
+#endif
+
+
 /* function prototypes */
 
 int  main (int argc, char *argv[]);
@@ -376,7 +386,7 @@
   /* row_bytes is the width x number of channels x (bit-depth / 8) */
     row_bytes = width * channels * ((bit_depth <= 8) ? 1 : 2);
 
-  if ((row_bytes == 0 || (size_t)height > ((size_t)(-1))/(size_t)row_bytes)
+  if ((row_bytes == 0 || (size_t)height > ((size_t)(-1))/(size_t)row_bytes))
   {
     /* too big */ 
     return FALSE;
@@ -513,7 +523,7 @@
   if (png_pixels != (unsigned char*) NULL)
     free (png_pixels);
 
-  PNG_UNUSED(raw) /* Quiet a Coverity defect */
+  PNGMINUS_UNUSED(raw); /* Quiet a Coverity defect */
 
   return TRUE;
 } /* end of pnm2png */