libs/wpp/preproc.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/libs/wpp/preproc.c b/libs/wpp/preproc.c
index 233d260..e4752a5 100644
--- a/libs/wpp/preproc.c
+++ b/libs/wpp/preproc.c
@@ -447,7 +447,12 @@ pp_entry_t *pp_add_macro(char *id, marg_t *args[], int nargs, mtext_t *exp)
  * Include management
  *-------------------------------------------------------------------------
  */
-#if defined(_Windows) || defined(__MSDOS__)
+#if ( defined(_Windows) || defined(_WINDOWS)  || defined(WIN32) || \
+      defined(_WIN32)   || defined(__WIN32__) || defined(__MSDOS__) )
+/*
+ * Windows system uses ':' as part of its path.
+ * Therefore use another separator character.
+ */
 #define INCLUDESEPARATOR	";"
 #else
 #define INCLUDESEPARATOR	":"