diff --git a/make/windows/makefiles/defs.make b/make/windows/makefiles/defs.make
index 7bb84ea2fd6fdef2c78fea396c3bae67eccca5d4..851fe4f48328c4b69625a224d0dd0a57c598556d 100644
--- a/make/windows/makefiles/defs.make
+++ b/make/windows/makefiles/defs.make
@@ -69,8 +69,20 @@ ifneq ($(shell $(ECHO) $(PROCESSOR_IDENTIFIER) | $(GREP) AMD64),)
   MAKE_ARGS += Platform_arch_model=x86_64
 endif
 
+ifneq ($(shell $(ECHO) $(PROCESSOR_IDENTIFIER) | $(GREP) EM64T),)
+  ARCH_DATA_MODEL=64
+  PLATFORM=windows-amd64
+  VM_PLATFORM=windows_amd64
+  HS_ARCH=x86
+  MAKE_ARGS += LP64=1
+  MAKE_ARGS += ARCH=x86
+  MAKE_ARGS += BUILDARCH=amd64
+  MAKE_ARGS += Platform_arch=x86
+  MAKE_ARGS += Platform_arch_model=x86_64
+endif
+
 # NB later OS versions than 2003 may report "Intel64"
-ifneq ($(shell $(ECHO) $(PROCESSOR_IDENTIFIER) | $(GREP) "EM64T\|Intel64"),)
+ifneq ($(shell $(ECHO) $(PROCESSOR_IDENTIFIER) | $(GREP) Intel64),)
   ARCH_DATA_MODEL=64
   PLATFORM=windows-amd64
   VM_PLATFORM=windows_amd64