diff --git a/glide2x/cvg/glide/src/glidesys.h b/glide2x/cvg/glide/src/glidesys.h
index ce2e1e2..c9c70c9 100644
--- a/glide2x/cvg/glide/src/glidesys.h
+++ b/glide2x/cvg/glide/src/glidesys.h
@@ -87,7 +87,7 @@ n** -----------------------------------------------------------------------
 /* Check for OS */
 #if defined(__IRIX__) || defined(__sparc__) || defined(__linux__)
 #  define GLIDE_OS        GLIDE_OS_UNIX
-#elif defined(__DOS__)
+#elif defined(__DOS__) || defined(__MSDOS__)
 #  define GLIDE_OS        GLIDE_OS_DOS32
 #elif defined(__WIN32__)
 #  define GLIDE_OS        GLIDE_OS_WIN32
diff --git a/glide2x/h3/glide/src/glidesys.h b/glide2x/h3/glide/src/glidesys.h
index 61b88f0..96d80e8 100644
--- a/glide2x/h3/glide/src/glidesys.h
+++ b/glide2x/h3/glide/src/glidesys.h
@@ -93,7 +93,7 @@ n** -----------------------------------------------------------------------
 /* Check for OS */
 #if defined(__IRIX__) || defined(__sparc__) || defined(__linux__)
 #  define GLIDE_OS        GLIDE_OS_UNIX
-#elif defined(__DOS__)
+#elif defined(__DOS__) || defined(__MSDOS__)
 #  define GLIDE_OS        GLIDE_OS_DOS32
 #elif defined(__WIN32__)
 #  define GLIDE_OS        GLIDE_OS_WIN32
diff --git a/glide2x/sst1/glide/src/glidesys.h b/glide2x/sst1/glide/src/glidesys.h
index fbc1e6e..7b995b6 100644
--- a/glide2x/sst1/glide/src/glidesys.h
+++ b/glide2x/sst1/glide/src/glidesys.h
@@ -69,7 +69,7 @@ n** -----------------------------------------------------------------------
 /* Check for OS */
 #if defined(__IRIX__) || defined(__sparc__) || defined(__linux__)
 #  define GLIDE_OS        GLIDE_OS_UNIX
-#elif defined(__DOS__)
+#elif defined(__DOS__) || defined(__MSDOS__)
 #  define GLIDE_OS        GLIDE_OS_DOS32
 #elif defined(__WIN32__)
 #  define GLIDE_OS        GLIDE_OS_WIN32
diff --git a/glide3x/cvg/glide3/src/glidesys.h b/glide3x/cvg/glide3/src/glidesys.h
index 6795a19..cc3e003 100644
--- a/glide3x/cvg/glide3/src/glidesys.h
+++ b/glide3x/cvg/glide3/src/glidesys.h
@@ -96,7 +96,7 @@ n** -----------------------------------------------------------------------
 /* Check for OS */
 #if defined(__IRIX__) || defined(__sparc__) || defined(__linux__)
 #  define GLIDE_OS        GLIDE_OS_UNIX
-#elif defined(__DOS__)
+#elif defined(__DOS__) || defined(__MSDOS__)
 #  define GLIDE_OS        GLIDE_OS_DOS32
 #elif defined(__WIN32__)
 #  define GLIDE_OS        GLIDE_OS_WIN32
diff --git a/glide3x/h3/glide3/src/glidesys.h b/glide3x/h3/glide3/src/glidesys.h
index 0a928ed..efe258f 100644
--- a/glide3x/h3/glide3/src/glidesys.h
+++ b/glide3x/h3/glide3/src/glidesys.h
@@ -107,7 +107,7 @@ n** -----------------------------------------------------------------------
 /* Check for OS */
 #if defined(__IRIX__) || defined(__sparc__) || defined(__linux__) || defined(__FreeBSD__)
 #  define GLIDE_OS        GLIDE_OS_UNIX
-#elif defined(__DOS__)
+#elif defined(__DOS__) || defined(__MSDOS__)
 #  define GLIDE_OS        GLIDE_OS_DOS32
 #elif defined(__WIN32__)
 #  define GLIDE_OS        GLIDE_OS_WIN32
diff --git a/glide3x/h5/glide3/src/glidesys.h b/glide3x/h5/glide3/src/glidesys.h
index fd6583c..e3f5d35 100644
--- a/glide3x/h5/glide3/src/glidesys.h
+++ b/glide3x/h5/glide3/src/glidesys.h
@@ -111,7 +111,7 @@ n** -----------------------------------------------------------------------
 #if defined(__IRIX__) || defined(__sparc__) || defined(__linux__) || \
 	defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__)
 #  define GLIDE_OS        GLIDE_OS_UNIX
-#elif defined(__DOS__)
+#elif defined(__DOS__) || defined(__MSDOS__)
 #  define GLIDE_OS        GLIDE_OS_DOS32
 #elif defined(__WIN32__)
 #  define GLIDE_OS        GLIDE_OS_WIN32
diff --git a/glide3x/sst1/glide3/src/glidesys.h b/glide3x/sst1/glide3/src/glidesys.h
index 4642b3f..31f7487 100644
--- a/glide3x/sst1/glide3/src/glidesys.h
+++ b/glide3x/sst1/glide3/src/glidesys.h
@@ -84,7 +84,7 @@ n** -----------------------------------------------------------------------
 /* Check for OS */
 #if defined(__IRIX__) || defined(__sparc__) || defined(__linux__)
 #  define GLIDE_OS        GLIDE_OS_UNIX
-#elif defined(__DOS__)
+#elif defined(__DOS__) || defined(__MSDOS__)
 #  define GLIDE_OS        GLIDE_OS_DOS32
 #elif defined(__WIN32__)
 #  define GLIDE_OS        GLIDE_OS_WIN32
diff --git a/swlibs/fxmisc/3dfx.h b/swlibs/fxmisc/3dfx.h
index 6403f2f..8a9ce25 100644
--- a/swlibs/fxmisc/3dfx.h
+++ b/swlibs/fxmisc/3dfx.h
@@ -27,7 +27,7 @@ typedef unsigned char   FxU8;
 typedef signed   char   FxI8;
 typedef unsigned short  FxU16;
 typedef signed   short  FxI16;
-#if defined(__DOS__)||defined(_WIN32)||defined(macintosh)
+#if defined(__DOS__) || defined(__MSDOS__) || defined(_WIN32) || defined(macintosh)
 typedef signed   long   FxI32;
 typedef unsigned long   FxU32;
 #else