diff --git a/ANNOUNCE b/ANNOUNCE
index c34d449ae..8ce75e580 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,4 +1,4 @@
-Libpng 1.6.31beta01 - June 28, 2017
+Libpng 1.6.31beta01 - July 1, 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.
@@ -60,7 +60,11 @@ Version 1.6.30rc02 [June 25, 2017]
 Version 1.6.30 [June 28, 2017]
   No changes.
 
-Version 1.6.31beta01 [June 28, 2017]
+Version 1.6.31beta01 [July 1, 2017]
+  Guard the definition of _POSIX_SOURCE in pngpriv.h (AIX already defines it;
+    bug report by Michael Felt).
+  Revised pngpriv.h to work around failure to compile arm/filter_neon.S
+    ("typedef" directive is unrecognized by the assembler).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/CHANGES b/CHANGES
index 09898d79b..26302965d 100644
--- a/CHANGES
+++ b/CHANGES
@@ -5855,7 +5855,11 @@ Version 1.6.30rc02 [June 25, 2017]
 Version 1.6.30 [June 28, 2017]
   No changes.
 
-Version 1.6.31beta01 [June 28, 2017]
+Version 1.6.31beta01 [July 1, 2017]
+  Guard the definition of _POSIX_SOURCE in pngpriv.h (AIX already defines it;
+    bug report by Michael Felt).
+  Revised pngpriv.h to work around failure to compile arm/filter_neon.S
+    ("typedef" directive is unrecognized by the assembler).
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/pngpriv.h b/pngpriv.h
index 5b81af631..510bd0051 100644
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -35,7 +35,9 @@
  * Windows/Visual Studio) there is no effect; the OS specific tests below are
  * still required (as of 2011-05-02.)
  */
-#define _POSIX_SOURCE 1 /* Just the POSIX 1003.1 and C89 APIs */
+#ifndef _POSIX_SOURCE
+# define _POSIX_SOURCE 1 /* Just the POSIX 1003.1 and C89 APIs */
+#endif
 
 #ifndef PNG_VERSION_INFO_ONLY
 /* Standard library headers not required by png.h: */
@@ -466,16 +468,21 @@
    static_cast<type>(static_cast<const void*>(value))
 #else
 #  define png_voidcast(type, value) (value)
-#  ifdef _WIN64
+#  if PNG_ARM_NEON_IMPLEMENTATION == 2 /* hand-coded assembler */
+                                       /* does not recognize "typedef" */
+#    define png_constcast(type, value) ((type)(value))
+#  else
+#    ifdef _WIN64
 #     ifdef __GNUC__
          typedef unsigned long long png_ptruint;
 #     else
          typedef unsigned __int64 png_ptruint;
 #     endif
-#  else
+#    else
       typedef unsigned long png_ptruint;
+#    endif
+#    define png_constcast(type, value) ((type)(png_ptruint)(const void*)(value))
 #  endif
-#  define png_constcast(type, value) ((type)(png_ptruint)(const void*)(value))
 #  define png_aligncast(type, value) ((void*)(value))
 #  define png_aligncastconst(type, value) ((const void*)(value))
 #endif /* __cplusplus */