diff --git a/SCons/Config/gnu b/SCons/Config/gnu
index 2da0c7f8..a4c229fd 100644
--- a/SCons/Config/gnu
+++ b/SCons/Config/gnu
@@ -256,7 +256,7 @@ if conf.CheckBigEndian():
 conf.Finish()
 
 if makensis_env['PLATFORM'] == 'hpux':
-	makensis_env.Append(CPPDEFINES = ['__ALLOW_UNALIGNED_DATA_ACCESS__'])
+	makensis_env.Append(CPPDEFINES = ['NSIS_HPUX_ALLOW_UNALIGNED_DATA_ACCESS'])
 	makensis_conf = makensis_env.Configure()
 	makensis_conf.CheckLib("unalign")
 	makensis_conf.CheckLib("hppa")
diff --git a/SCons/Config/hpc++ b/SCons/Config/hpc++
index 3c0ebd1d..9df2905c 100644
--- a/SCons/Config/hpc++
+++ b/SCons/Config/hpc++
@@ -86,7 +86,7 @@ if makensis_conf.CheckBigEndian():
 	makensis_env.Append(CPPDEFINES = ['__BIG_ENDIAN__'])
 
 if makensis_env['PLATFORM'] == 'hpux':
-	makensis_env.Append(CPPDEFINES = ['__ALLOW_UNALIGNED_DATA_ACCESS__'])
+	makensis_env.Append(CPPDEFINES = ['NSIS_HPUX_ALLOW_UNALIGNED_DATA_ACCESS'])
 	makensis_conf.CheckLib("unalign")
 	makensis_conf.CheckLib("hppa")
 
diff --git a/Source/makenssi.cpp b/Source/makenssi.cpp
index 9e791905..8af6741b 100644
--- a/Source/makenssi.cpp
+++ b/Source/makenssi.cpp
@@ -246,7 +246,7 @@ static int change_to_script_dir(CEXEBuild& build, string& script)
 int main(int argc, char **argv)
 {
 
-#ifdef __ALLOW_UNALIGNED_DATA_ACCESS__
+#ifdef NSIS_HPUX_ALLOW_UNALIGNED_DATA_ACCESS
   extern "C" void allow_unaligned_data_access();
   allow_unaligned_data_access();
 #endif