diff --git a/Docs/src/history.but b/Docs/src/history.but
index c4919226..73f7afe0 100644
--- a/Docs/src/history.but
+++ b/Docs/src/history.but
@@ -34,6 +34,8 @@ Released on ?, 2014
 
 \b Fixed !macroundef
 
+\b Added IsWow64 to x64.nsh
+
 \S2{} Translations
 
 \b Added Armenian (Hrant Ohanyan)
diff --git a/Include/LogicLib.nsh b/Include/LogicLib.nsh
index 4fdd527f..dc1c05d0 100644
--- a/Include/LogicLib.nsh
+++ b/Include/LogicLib.nsh
@@ -93,6 +93,10 @@
     !endif
   !macroend
 
+  !macro LogicLib_JumpToBranch _Jump _Skip
+    StrCmp "" ""  `${_Jump}` ${_Skip}
+  !macroend
+
   !macro _IncreaseCounter
     !define _LOGICLIB_COUNTER ${LOGICLIB_COUNTER}
     !undef LOGICLIB_COUNTER
diff --git a/Include/x64.nsh b/Include/x64.nsh
index a35e0990..e66fb859 100644
--- a/Include/x64.nsh
+++ b/Include/x64.nsh
@@ -4,7 +4,8 @@
 ;
 ; A few simple macros to handle installations on x64 machines.
 ;
-; RunningX64 checks if the installer is running on x64.
+; RunningX64 checks if the installer is running on a 64-bit OS.
+; IsWow64 checks if the installer is a 32-bit application running on a 64-bit OS.
 ;
 ;   ${If} ${RunningX64}
 ;     MessageBox MB_OK "running on x64"
@@ -25,30 +26,36 @@
 
 !include LogicLib.nsh
 
-!macro _RunningX64 _a _b _t _f
+
+!define IsWow64 `"" IsWow64 ""`
+!macro _IsWow64 _a _b _t _f
   !insertmacro _LOGICLIB_TEMP
   System::Call kernel32::GetCurrentProcess()p.s
-  System::Call kernel32::IsWow64Process(ps,*i.s)
+  System::Call kernel32::IsWow64Process(ps,*i0s)
   Pop $_LOGICLIB_TEMP
   !insertmacro _!= $_LOGICLIB_TEMP 0 `${_t}` `${_f}`
 !macroend
 
+
 !define RunningX64 `"" RunningX64 ""`
-
-!macro DisableX64FSRedirection
-
-  System::Call kernel32::Wow64EnableWow64FsRedirection(i0)
-
+!macro _RunningX64 _a _b _t _f 
+  !if ${NSIS_PTR_SIZE} > 4
+    !insertmacro LogicLib_JumpToBranch `${_t}` `${_f}`
+  !else
+    !insertmacro _IsWow64 `${_a}` `${_b}` `${_t}` `${_f}`
+  !endif
 !macroend
 
+
 !define DisableX64FSRedirection "!insertmacro DisableX64FSRedirection"
-
-!macro EnableX64FSRedirection
-
-  System::Call kernel32::Wow64EnableWow64FsRedirection(i1)
-
+!macro DisableX64FSRedirection
+  System::Call kernel32::Wow64EnableWow64FsRedirection(i0)
 !macroend
 
 !define EnableX64FSRedirection "!insertmacro EnableX64FSRedirection"
+!macro EnableX64FSRedirection
+  System::Call kernel32::Wow64EnableWow64FsRedirection(i1)
+!macroend
+
 
 !endif # !___X64__NSH___
diff --git a/Source/build.cpp b/Source/build.cpp
index 09a4a6fc..93e03728 100644
--- a/Source/build.cpp
+++ b/Source/build.cpp
@@ -3767,6 +3767,13 @@ int CEXEBuild::set_target_architecture_data()
   }
   definedlist.set(_T("NSIS_PTR_SIZE"), is_target_64bit() ? _T("8") : _T("4"));
 
+  definedlist.del(_T("NSIS_IX86"));
+  definedlist.del(_T("NSIS_AMD64"));
+  if (TARGET_AMD64 == m_target_type)
+    definedlist.set(_T("NSIS_AMD64"));
+  else
+    definedlist.set(_T("NSIS_IX86"), build_unicode ? _T("400") : _T("300"));
+
   return PS_OK;
 }