diff --git a/CMakeLists.txt b/CMakeLists.txt
index 34d2c689d..9877af89e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -205,9 +205,6 @@ message(STATUS "PYTHON_EXECUTABLE: ${PYTHON_EXECUTABLE}")
 include(${CMAKE_SOURCE_DIR}/cmake/target_arch_detect.cmake)
 detect_target_architecture(TARGET_ARCHITECTURE)
 message(STATUS "Detected target architecture: ${TARGET_ARCHITECTURE}")
-if ("${TARGET_ARCHITECTURE}" STREQUAL "x86_64")
-  list(APPEND Z3_COMPONENT_CXX_DEFINES "-D_AMD64_")
-endif()
 
 
 ################################################################################
diff --git a/scripts/mk_util.py b/scripts/mk_util.py
index ad643c9ba..023158573 100644
--- a/scripts/mk_util.py
+++ b/scripts/mk_util.py
@@ -2706,7 +2706,7 @@ def mk_config():
                 'SLINK_FLAGS=/nologo /LDd\n' % static_opt)
             if VS_X64:
                 config.write(
-                    'CXXFLAGS=/c /Zi /nologo /W3 /WX- /Od /Oy- /D WIN32 /D _AMD64_ /D _DEBUG /D Z3DEBUG /D _CONSOLE /D _TRACE /D _WINDOWS /Gm- /EHsc /RTC1 /GS /fp:precise /Zc:wchar_t /Zc:forScope /Gd /analyze- %s %s\n' % (extra_opt, static_opt))
+                    'CXXFLAGS=/c /Zi /nologo /W3 /WX- /Od /Oy- /D WIN32 /D _DEBUG /D Z3DEBUG /D _CONSOLE /D _TRACE /D _WINDOWS /Gm- /EHsc /RTC1 /GS /fp:precise /Zc:wchar_t /Zc:forScope /Gd /analyze- %s %s\n' % (extra_opt, static_opt))
                 config.write(
                     'LINK_EXTRA_FLAGS=/link /DEBUG /MACHINE:X64 /SUBSYSTEM:CONSOLE /INCREMENTAL:NO /STACK:8388608 /OPT:REF /OPT:ICF /TLBID:1 /DYNAMICBASE /NXCOMPAT %s\n'
                     'SLINK_EXTRA_FLAGS=/link /DEBUG /MACHINE:X64 /SUBSYSTEM:WINDOWS /INCREMENTAL:NO /STACK:8388608 /OPT:REF /OPT:ICF /TLBID:1 %s %s\n' % (link_extra_opt, maybe_disable_dynamic_base, link_extra_opt))
@@ -2731,7 +2731,7 @@ def mk_config():
                 extra_opt = '%s /D _TRACE ' % extra_opt
             if VS_X64:
                 config.write(
-                    'CXXFLAGS=/c%s /Zi /nologo /W3 /WX- /O2 /D _EXTERNAL_RELEASE /D WIN32 /D NDEBUG /D _LIB /D _WINDOWS /D _AMD64_ /D _UNICODE /D UNICODE /Gm- /EHsc /GS /fp:precise /Zc:wchar_t /Zc:forScope /Gd /TP %s %s\n' % (GL, extra_opt, static_opt))
+                    'CXXFLAGS=/c%s /Zi /nologo /W3 /WX- /O2 /D _EXTERNAL_RELEASE /D WIN32 /D NDEBUG /D _LIB /D _WINDOWS /D _UNICODE /D UNICODE /Gm- /EHsc /GS /fp:precise /Zc:wchar_t /Zc:forScope /Gd /TP %s %s\n' % (GL, extra_opt, static_opt))
                 config.write(
                     'LINK_EXTRA_FLAGS=/link%s /MACHINE:X64 /SUBSYSTEM:CONSOLE /INCREMENTAL:NO /STACK:8388608 %s\n'
                     'SLINK_EXTRA_FLAGS=/link%s /MACHINE:X64 /SUBSYSTEM:WINDOWS /INCREMENTAL:NO /STACK:8388608 %s\n' % (LTCG, link_extra_opt, LTCG, link_extra_opt))
@@ -2853,7 +2853,6 @@ def mk_config():
         if is64():
             if not sysname.startswith('CYGWIN') and not sysname.startswith('MSYS') and not sysname.startswith('MINGW'):
                 CXXFLAGS     = '%s -fPIC' % CXXFLAGS
-            CPPFLAGS     = '%s -D_AMD64_' % CPPFLAGS
             if sysname == 'Linux':
                 CPPFLAGS = '%s -D_USE_THREAD_LOCAL' % CPPFLAGS
         elif not LINUX_X64:
diff --git a/scripts/update_api.py b/scripts/update_api.py
index 13f1aaf9c..161c783e8 100755
--- a/scripts/update_api.py
+++ b/scripts/update_api.py
@@ -584,7 +584,7 @@ def mk_java(java_dir, package_name):
     java_wrapper.write('extern "C" {\n')
     java_wrapper.write('#endif\n\n')
     java_wrapper.write('#ifdef __GNUC__\n#if __GNUC__ >= 4\n#define DLL_VIS __attribute__ ((visibility ("default")))\n#else\n#define DLL_VIS\n#endif\n#else\n#define DLL_VIS\n#endif\n\n')
-    java_wrapper.write('#if defined(_M_X64) || defined(_AMD64_)\n\n')
+    java_wrapper.write('#if defined(__LP64__) || defined(_WIN64)\n\n')
     java_wrapper.write('#define GETLONGAELEMS(T,OLD,NEW)                                   \\\n')
     java_wrapper.write('  T * NEW = (OLD == 0) ? 0 : (T*) jenv->GetLongArrayElements(OLD, NULL);\n')
     java_wrapper.write('#define RELEASELONGAELEMS(OLD,NEW)                                 \\\n')
diff --git a/src/api/java/CMakeLists.txt b/src/api/java/CMakeLists.txt
index 302b3d5bd..c2d73ffb1 100644
--- a/src/api/java/CMakeLists.txt
+++ b/src/api/java/CMakeLists.txt
@@ -39,8 +39,7 @@ add_library(z3java SHARED ${Z3_JAVA_NATIVE_CPP})
 target_link_libraries(z3java PRIVATE libz3)
 # FIXME:
 # Not sure if using all the flags used by the Z3 components is really necessary
-# here.  At the bare minimum setting _AMD64_ depending on the target is
-# necessary but seeing as the Python build system uses all the flags used for building
+# here. The Python build system uses all the flags used for building
 # Z3's components to build ``Native.cpp`` lets do the same for now.
 target_compile_options(z3java PRIVATE ${Z3_COMPONENT_CXX_FLAGS})
 target_compile_definitions(z3java PRIVATE ${Z3_COMPONENT_CXX_DEFINES})
diff --git a/src/sat/sat_clause.cpp b/src/sat/sat_clause.cpp
index 3cbd3015b..31a4bba72 100644
--- a/src/sat/sat_clause.cpp
+++ b/src/sat/sat_clause.cpp
@@ -111,7 +111,7 @@ namespace sat {
 
     clause_offset clause::get_new_offset() const {
         unsigned o1 = m_lits[0].index();
-#if defined(_AMD64_) || defined(_M_IA64)
+#if defined(__LP64__) || defined(_WIN64)
         if (sizeof(clause_offset) == 8) {
             unsigned o2 = m_lits[1].index();
             return (clause_offset)o1 + (((clause_offset)o2) << 32);
@@ -122,7 +122,7 @@ namespace sat {
 
     void clause::set_new_offset(clause_offset offset) {
         m_lits[0] = to_literal(static_cast<unsigned>(offset));
-#if defined(_AMD64_) || defined(_M_IA64)
+#if defined(__LP64__) || defined(_WIN64)
         if (sizeof(offset) == 8) {
             m_lits[1] = to_literal(static_cast<unsigned>(offset >> 32));
         }
diff --git a/src/shell/main.cpp b/src/shell/main.cpp
index 3b97d4462..b036628b1 100644
--- a/src/shell/main.cpp
+++ b/src/shell/main.cpp
@@ -60,7 +60,7 @@ void error(const char * msg) {
 void display_usage() {
     std::cout << "Z3 [version " << Z3_MAJOR_VERSION << "." << Z3_MINOR_VERSION << "." << Z3_BUILD_NUMBER;
     std::cout << " - ";
-#ifdef _AMD64_
+#if defined(__LP64__) || defined(_WIN64)
     std::cout << "64";
 #else
     std::cout << "32";
@@ -161,7 +161,7 @@ void parse_cmd_line_args(int argc, char ** argv) {
             if (strcmp(opt_name, "version") == 0) {
                 std::cout << "Z3 version " << Z3_MAJOR_VERSION << "." << Z3_MINOR_VERSION << "." << Z3_BUILD_NUMBER;
                 std::cout << " - ";
-#ifdef _AMD64_
+#if defined(__LP64__) || defined(_WIN64)
                 std::cout << "64";
 #else
                 std::cout << "32";
diff --git a/src/smt/watch_list.cpp b/src/smt/watch_list.cpp
index 778e93021..f95e1c571 100644
--- a/src/smt/watch_list.cpp
+++ b/src/smt/watch_list.cpp
@@ -21,7 +21,7 @@ Revision History:
 namespace smt {
 
 #define DEFAULT_WATCH_LIST_SIZE (sizeof(clause *) * 4)
-#ifdef _AMD64_
+#if defined(__LP64__) || defined(_WIN64)
 // make sure data is aligned in 64 bit machines
 #define HEADER_SIZE (4 * sizeof(unsigned)) 
 #else
@@ -38,7 +38,7 @@ namespace smt {
         if (m_data == nullptr) {
             unsigned size       = DEFAULT_WATCH_LIST_SIZE + HEADER_SIZE;
             unsigned * mem      = reinterpret_cast<unsigned*>(alloc_svect(char, size));
-#ifdef _AMD64_
+#if defined(__LP64__) || defined(_WIN64)
             ++mem;  // make sure data is aligned in 64 bit machines
 #endif
             *mem                = 0;
@@ -61,7 +61,7 @@ namespace smt {
             unsigned new_capacity   = (((curr_capacity * 3 + sizeof(clause *)) >> 1)+3)&~3U;
             unsigned * mem          = reinterpret_cast<unsigned*>(alloc_svect(char, new_capacity + HEADER_SIZE));
             unsigned curr_end_cls   = end_cls_core();
-#ifdef _AMD64_
+#if defined(__LP64__) || defined(_WIN64)
             ++mem;  // make sure data is aligned in 64 bit machines
 #endif
             *mem                    = curr_end_cls;
diff --git a/src/util/hwf.cpp b/src/util/hwf.cpp
index e6393adbd..4a7a0b7e4 100644
--- a/src/util/hwf.cpp
+++ b/src/util/hwf.cpp
@@ -61,7 +61,7 @@ hwf_manager::hwf_manager() :
     m_mpz_manager(m_mpq_manager)
 {
 #ifdef _WINDOWS
-#if defined(_AMD64_) || defined(_M_IA64)
+#if defined(_WIN64)
     // Precision control is not supported on x64.
     // See: http://msdn.microsoft.com/en-us/library/e9b52ceh(VS.110).aspx
     // CMW: I think this is okay though, the compiler will chose the right instructions
@@ -557,7 +557,7 @@ void hwf_manager::mk_ninf(hwf & o) {
 }
 
 #ifdef _WINDOWS
-#if defined(_AMD64_) || defined(_M_IA64)
+#if defined(_WIN64)
 #ifdef USE_INTRINSICS
 #define SETRM(RM) _MM_SET_ROUNDING_MODE(RM)
 #else
diff --git a/src/util/machine.h b/src/util/machine.h
index 70baee41e..1ccff6330 100644
--- a/src/util/machine.h
+++ b/src/util/machine.h
@@ -20,7 +20,7 @@ Revision History:
 #ifndef MACHINE_H_
 #define MACHINE_H_
 
-#ifdef _AMD64_
+#if defined(__LP64__) || defined(_WIN64)
 #define PTR_ALIGNMENT 3
 #else
 #define PTR_ALIGNMENT 2
diff --git a/src/util/mpn.h b/src/util/mpn.h
index ea20fc42b..bae972b0c 100644
--- a/src/util/mpn.h
+++ b/src/util/mpn.h
@@ -61,7 +61,7 @@ public:
     char * to_string(mpn_digit const * a, size_t lng,
                      char * buf, size_t lbuf) const;
 private:
-    #ifdef _AMD64_
+    #if defined(__LP64__) || defined(_WIN64)
     class  mpn_sbuffer : public sbuffer<mpn_digit> {
     public:
         mpn_sbuffer() : sbuffer<mpn_digit>() {}
diff --git a/src/util/mpz.cpp b/src/util/mpz.cpp
index af95e1a2a..0d3a6040d 100644
--- a/src/util/mpz.cpp
+++ b/src/util/mpz.cpp
@@ -56,7 +56,7 @@ Revision History:
 #define _trailing_zeros32(X) _tzcnt_u32(X)
 #endif
 
-#if defined(_AMD64_) 
+#if defined(__LP64__) || defined(_WIN64)
  #if defined(__GNUC__)
  #define _trailing_zeros64(X) __builtin_ctzll(X)
  #else
diff --git a/src/util/symbol.h b/src/util/symbol.h
index 40844cf3b..90a4eeb38 100644
--- a/src/util/symbol.h
+++ b/src/util/symbol.h
@@ -56,7 +56,7 @@ public:
     explicit symbol(char const * d);
     explicit symbol(unsigned idx):
         m_data(BOXTAGINT(char const *, idx, 1)) {
-#ifndef _AMD64_
+#if !defined(__LP64__) && !defined(_WIN64)
         SASSERT(idx < (SIZE_MAX >> PTR_ALIGNMENT));
 #endif
     }