kc3-lang/libffi

diff --git a/README.md b/README.md
index b4e58f6..3d89f7b 100644
--- a/README.md
+++ b/README.md
@@ -154,7 +154,7 @@ It's also possible to build libffi on Windows platforms with
 Microsoft's Visual C++ compiler.  In this case, use the msvcc.sh
 wrapper script during configuration like so:
 
-    path/to/configure CC=path/to/msvcc.sh CXX=path/to/msvcc.sh LD=link CPP="cl -nologo -EP"
+    path/to/configure CC=path/to/msvcc.sh CXX=path/to/msvcc.sh LD=link CPP="cl -nologo -EP" CPPFLAGS="-DFFI_BUILDING_DLL"
 
 For 64-bit Windows builds, use ``CC="path/to/msvcc.sh -m64"`` and
 ``CXX="path/to/msvcc.sh -m64"``.  You may also need to specify
@@ -163,7 +163,7 @@ For 64-bit Windows builds, use ``CC="path/to/msvcc.sh -m64"`` and
 It is also possible to build libffi on Windows platforms with the LLVM
 project's clang-cl compiler, like below:
 
-    path/to/configure CC="path/to/msvcc.sh -clang-cl" CXX="path/to/msvcc.sh -clang-cl" LD=link CPP="clang-cl -EP"
+    path/to/configure CC="path/to/msvcc.sh -clang-cl" CXX="path/to/msvcc.sh -clang-cl" LD=link CPP="clang-cl -EP" 
 
 When building with MSVC under a MingW environment, you may need to
 remove the line in configure that sets 'fix_srcfile_path' to a 'cygpath'