diff --git a/appveyor.yml b/appveyor.yml
index 434186f..6ce28df 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -45,6 +45,19 @@ environment:
     B2_VARIANT: variant=release,debug
 
   matrix:
+    - FLAVOR: Visual Studio 2019 All Modes
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
+      TOOLSET: msvc-14.2
+      B2_ADDRESS_MODEL: address-model=64,32
+      CXXSTD: 14,17,latest
+
+    - FLAVOR: Visual Studio 2019 New Preprocessor
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
+      TOOLSET: msvc-14.2
+      B2_ADDRESS_MODEL: address-model=64,32
+      CXXFLAGS: cxxflags="/Zc:preprocessor"
+      CXXSTD: 14,17,latest
+
     - FLAVOR: Visual Studio 2017 C++2a Strict
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
       TOOLSET: msvc-14.1
@@ -68,9 +81,10 @@ environment:
       TOOLSET: msvc-14.0
       B2_ADDRESS_MODEL: address-model=64,32
 
-    - FLAVOR: Visual Studio 2010, 2012, 2013
-      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2013
-      TOOLSET: msvc-10.0,msvc-11.0,msvc-12.0
+    - FLAVOR: Visual Studio 2012
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      TOOLSET: msvc-12.0
+      B2_ADDRESS_MODEL: address-model=64,32
 
     - FLAVOR: cygwin (32-bit)
       APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
@@ -104,7 +118,7 @@ environment:
       ARCH: x86_64
       B2_ADDRESS_MODEL: address-model=64
       CXXSTD: 11,17
-      DEFINES: define=__USE_ISOC99
+      B2_DEFINES: define=__USE_ISOC99
       SCRIPT: ci\appveyor\mingw.bat
 
 install:
diff --git a/include/boost/mpl/aux_/preprocessor/enum.hpp b/include/boost/mpl/aux_/preprocessor/enum.hpp
index 64c5e6a..92c5031 100644
--- a/include/boost/mpl/aux_/preprocessor/enum.hpp
+++ b/include/boost/mpl/aux_/preprocessor/enum.hpp
@@ -29,6 +29,10 @@
     BOOST_PP_CAT(BOOST_MPL_PP_ENUM_,n)(param) \
     /**/
     
+#   define BOOST_MPL_PP_ENUM_Z(z_ignored, n, param) \
+    BOOST_PP_CAT(BOOST_MPL_PP_ENUM_,n)(param) \
+    /**/
+    
 #   define BOOST_MPL_PP_ENUM_0(p)
 #   define BOOST_MPL_PP_ENUM_1(p) p
 #   define BOOST_MPL_PP_ENUM_2(p) p,p
@@ -57,6 +61,14 @@
         ) \
     /**/
 
+#   define BOOST_MPL_PP_ENUM_Z(z, n, param) \
+    BOOST_PP_REPEAT_ ## z( \
+          n \
+        , BOOST_MPL_PP_AUX_ENUM_FUNC \
+        , param \
+        ) \
+    /**/
+
 #endif
 
 #endif // BOOST_MPL_AUX_PREPROCESSOR_ENUM_HPP_INCLUDED
diff --git a/include/boost/mpl/aux_/preprocessor/params.hpp b/include/boost/mpl/aux_/preprocessor/params.hpp
index acad321..c3ee6c1 100644
--- a/include/boost/mpl/aux_/preprocessor/params.hpp
+++ b/include/boost/mpl/aux_/preprocessor/params.hpp
@@ -29,6 +29,10 @@
     BOOST_PP_CAT(BOOST_MPL_PP_PARAMS_,n)(p) \
     /**/
 
+#   define BOOST_MPL_PP_PARAMS_Z(z_ignored,n,p) \
+    BOOST_PP_CAT(BOOST_MPL_PP_PARAMS_,n)(p) \
+    /**/
+
 #   define BOOST_MPL_PP_PARAMS_0(p)
 #   define BOOST_MPL_PP_PARAMS_1(p) p##1
 #   define BOOST_MPL_PP_PARAMS_2(p) p##1,p##2
@@ -60,6 +64,14 @@
         ) \
     /**/
 
+#   define BOOST_MPL_PP_PARAMS_Z(z, n, param) \
+    BOOST_PP_REPEAT_ ## z( \
+          n \
+        , BOOST_MPL_PP_AUX_PARAM_FUNC \
+        , param \
+        ) \
+    /**/
+
 #endif 
 
 #endif // BOOST_MPL_AUX_PREPROCESSOR_PARAMS_HPP_INCLUDED
diff --git a/include/boost/mpl/has_xxx.hpp b/include/boost/mpl/has_xxx.hpp
index 8a65c1f..a59c35d 100644
--- a/include/boost/mpl/has_xxx.hpp
+++ b/include/boost/mpl/has_xxx.hpp
@@ -334,7 +334,7 @@ struct trait \
 // correct name but different number of arguments.
 #   define BOOST_MPL_HAS_MEMBER_MULTI_SUBSTITUTE(z, n, args) \
       template< \
-          template< BOOST_PP_ENUM_PARAMS(BOOST_PP_INC(n), typename V) > class V \
+          template< BOOST_PP_ENUM_PARAMS_Z(z, BOOST_PP_INC(n), typename V) > class V \
        > \
       struct BOOST_MPL_HAS_MEMBER_INTROSPECTION_SUBSTITUTE_NAME(args, n) { \
       }; \
@@ -503,7 +503,7 @@ struct trait \
                  z, n, args \
              ) \
         template< \
-             template< BOOST_PP_ENUM_PARAMS(BOOST_PP_INC(n), typename U) > class U \
+             template< BOOST_PP_ENUM_PARAMS_Z(z, BOOST_PP_INC(n), typename U) > class U \
         > \
         struct BOOST_MPL_HAS_MEMBER_INTROSPECTION_SUBSTITUTE_NAME_WITH_TEMPLATE_SFINAE( \
                 args, n \
diff --git a/include/boost/mpl/string.hpp b/include/boost/mpl/string.hpp
index e789856..fd3100c 100644
--- a/include/boost/mpl/string.hpp
+++ b/include/boost/mpl/string.hpp
@@ -500,11 +500,11 @@ namespace boost { namespace mpl
     };
 
     #define M0(z, n, data)                                                                            \
-    template<BOOST_PP_ENUM_PARAMS(BOOST_MPL_STRING_MAX_PARAMS, int C), int J>                         \
-    struct string_iterator<mpl::string<BOOST_PP_ENUM_PARAMS(BOOST_MPL_STRING_MAX_PARAMS, C)>, n, J>   \
+    template<BOOST_PP_ENUM_PARAMS_Z(z, BOOST_MPL_STRING_MAX_PARAMS, int C), int J>                    \
+    struct string_iterator<mpl::string<BOOST_PP_ENUM_PARAMS_Z(z, BOOST_MPL_STRING_MAX_PARAMS, C)>, n, J> \
     {                                                                                                 \
         enum { eomc_ = (BOOST_MPL_MULTICHAR_LENGTH(BOOST_PP_CAT(C, n)) == J + 1) };                   \
-        typedef mpl::string<BOOST_PP_ENUM_PARAMS(BOOST_MPL_STRING_MAX_PARAMS, C)> string;             \
+        typedef mpl::string<BOOST_PP_ENUM_PARAMS_Z(z, BOOST_MPL_STRING_MAX_PARAMS, C)> string;        \
         typedef std::bidirectional_iterator_tag category;                                             \
         typedef                                                                                       \
             mpl::string_iterator<string, n + eomc_, eomc_ ? 0 : J + 1>                                \
@@ -514,11 +514,11 @@ namespace boost { namespace mpl
         prior;                                                                                        \
         typedef mpl::char_<BOOST_MPL_MULTICHAR_AT(BOOST_PP_CAT(C, n), J)> type;                       \
     };                                                                                                \
-    template<BOOST_PP_ENUM_PARAMS(BOOST_MPL_STRING_MAX_PARAMS, int C)>                                \
-    struct string_iterator<mpl::string<BOOST_PP_ENUM_PARAMS(BOOST_MPL_STRING_MAX_PARAMS, C)>, n, 0>   \
+    template<BOOST_PP_ENUM_PARAMS_Z(z, BOOST_MPL_STRING_MAX_PARAMS, int C)>                           \
+    struct string_iterator<mpl::string<BOOST_PP_ENUM_PARAMS_Z(z, BOOST_MPL_STRING_MAX_PARAMS, C)>, n, 0> \
     {                                                                                                 \
         enum { eomc_ = (BOOST_MPL_MULTICHAR_LENGTH(BOOST_PP_CAT(C, n)) == 1) };                       \
-        typedef mpl::string<BOOST_PP_ENUM_PARAMS(BOOST_MPL_STRING_MAX_PARAMS, C)> string;             \
+        typedef mpl::string<BOOST_PP_ENUM_PARAMS_Z(z, BOOST_MPL_STRING_MAX_PARAMS, C)> string;        \
         typedef std::bidirectional_iterator_tag category;                                             \
         typedef                                                                                       \
             mpl::string_iterator<string, n + eomc_, !eomc_>                                           \
diff --git a/test/apply_wrap.cpp b/test/apply_wrap.cpp
index 9c45f2e..851a817 100644
--- a/test/apply_wrap.cpp
+++ b/test/apply_wrap.cpp
@@ -24,14 +24,14 @@
 #include <boost/preprocessor/cat.hpp>
 
 #if !defined(BOOST_MPL_CFG_NO_DEFAULT_PARAMETERS_IN_NESTED_TEMPLATES)
-#   define APPLY_0_FUNC_DEF(i) \
+#   define APPLY_0_FUNC_DEF(z_ignored,i) \
     struct f0 \
     { \
         template< typename T = int > struct apply { typedef char type; }; \
     }; \
 /**/
 #else
-#   define APPLY_0_FUNC_DEF(i) \
+#   define APPLY_0_FUNC_DEF(z_ignored,i) \
     struct f0 \
     { \
         template< typename T > struct apply { typedef char type; }; \
@@ -39,16 +39,16 @@
 /**/
 #endif
 
-#define APPLY_N_FUNC_DEF(i) \
+#define APPLY_N_FUNC_DEF(z,i) \
     struct first##i \
     { \
-        template< BOOST_MPL_PP_PARAMS(i, typename U) > \
+        template< BOOST_MPL_PP_PARAMS_Z(z, i, typename U) > \
         struct apply { typedef U1 type; }; \
     }; \
     \
     struct last##i \
     { \
-        template< BOOST_MPL_PP_PARAMS(i, typename U) > \
+        template< BOOST_MPL_PP_PARAMS_Z(z, i, typename U) > \
         struct apply { typedef BOOST_PP_CAT(U,i) type; }; \
     }; \
 /**/
@@ -58,7 +58,7 @@
           i \
         , APPLY_N_FUNC_DEF \
         , APPLY_0_FUNC_DEF \
-        )(i) \
+        )(z,i) \
 /**/
 
 namespace { namespace test {
@@ -73,22 +73,22 @@ struct g0 { struct apply { typedef char type; }; };
 
 }}
 
-#define APPLY_0_TEST(i, apply_) \
+#define APPLY_0_TEST(z_ignored, i, apply_) \
     typedef apply_<test::f##i>::type t; \
     { MPL_ASSERT(( boost::is_same<t, char> )); } \
 /**/
 
-#define APPLY_N_TEST(i, apply_) \
+#define APPLY_N_TEST(z, i, apply_) \
     typedef apply_< \
           test::first##i \
         , char \
         BOOST_PP_COMMA_IF(BOOST_PP_DEC(i)) \
-        BOOST_MPL_PP_ENUM(BOOST_PP_DEC(i), int) \
+        BOOST_MPL_PP_ENUM_Z(z, BOOST_PP_DEC(i), int) \
         >::type t1##i; \
     \
     typedef apply_< \
           test::last##i \
-        , BOOST_MPL_PP_ENUM(BOOST_PP_DEC(i), int) \
+        , BOOST_MPL_PP_ENUM_Z(z, BOOST_PP_DEC(i), int) \
         BOOST_PP_COMMA_IF(BOOST_PP_DEC(i)) char \
         >::type t2##i; \
     { MPL_ASSERT(( boost::is_same<t1##i, char> )); } \
@@ -100,7 +100,7 @@ struct g0 { struct apply { typedef char type; }; };
           i \
         , APPLY_N_TEST \
         , APPLY_0_TEST \
-        )(i, BOOST_PP_CAT(apply_wrap,i)) \
+        )(z, i, BOOST_PP_CAT(apply_wrap,i)) \
 /**/
 
 
diff --git a/test/aux_/increased_arity.cpp b/test/aux_/increased_arity.cpp
index 47a433d..1bfe192 100644
--- a/test/aux_/increased_arity.cpp
+++ b/test/aux_/increased_arity.cpp
@@ -25,11 +25,11 @@
 #include <boost/preprocessor/enum_params.hpp>
 #include <boost/preprocessor/facilities/intercept.hpp>
 
-#define TEST_N_ARY(unused1, N, unused2) \
+#define TEST_N_ARY(z, N, unused2) \
     static_assert_< \
         apply< \
-            and_<BOOST_PP_ENUM_PARAMS(N, _ BOOST_PP_INTERCEPT)>, \
-            BOOST_PP_ENUM_PARAMS(N, true_ BOOST_PP_INTERCEPT) \
+            and_<BOOST_PP_ENUM_PARAMS_Z(z, N, _ BOOST_PP_INTERCEPT)>, \
+            BOOST_PP_ENUM_PARAMS_Z(z, N, true_ BOOST_PP_INTERCEPT) \
         > \
     >(); \
 /**/