diff --git a/src/gvcore/jpegformattype.cpp b/src/gvcore/jpegformattype.cpp
index 81f9edb..ea5cdaa 100644
--- a/src/gvcore/jpegformattype.cpp
+++ b/src/gvcore/jpegformattype.cpp
@@ -29,11 +29,7 @@
 // System
 #include <stdio.h>
 #include <setjmp.h>
-extern "C" {
-#define XMD_H
 #include <jpeglib.h>
-#undef const
-}
 
 // TQt
 #include <tqdatetime.h>
diff --git a/src/gvcore/mngformattype.cpp b/src/gvcore/mngformattype.cpp
index 2ce2f1c..b3b37a5 100644
--- a/src/gvcore/mngformattype.cpp
+++ b/src/gvcore/mngformattype.cpp
@@ -85,13 +85,6 @@
 #include "tqasyncimageio.h"
 #include "tqiodevice.h"
 
-// Define XMD_H prohibits the included headers of libmng.h to typedef INT32.
-// This is needed for Borland with STL support, since in that case, INT32 is
-// already defined by some Borland header.
-#define XMD_H
-#if defined(TQ_OS_UNIXWARE)
-#  define HAVE_BOOLEAN  // libjpeg under Unixware seems to need this
-#endif
 #include <libmng.h>
 #include <stdlib.h>
 
diff --git a/src/gvcore/thumbnailloadjob.cpp b/src/gvcore/thumbnailloadjob.cpp
index 826d641..7d3a11f 100644
--- a/src/gvcore/thumbnailloadjob.cpp
+++ b/src/gvcore/thumbnailloadjob.cpp
@@ -48,10 +48,7 @@
 
 // libjpeg 
 #include <setjmp.h>
-#define XMD_H
-extern "C" {
 #include <jpeglib.h>
-}
 
 // Local
 #include "cache.h"
diff --git a/src/imageutils/jpegerrormanager.h b/src/imageutils/jpegerrormanager.h
index 49a0e80..00898bc 100644
--- a/src/imageutils/jpegerrormanager.h
+++ b/src/imageutils/jpegerrormanager.h
@@ -21,12 +21,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 #define JPEGERRORMANAGER_H
 
 #include <setjmp.h>
-
-extern "C" {
-#define XMD_H
 #include <jpeglib.h>
-#undef const
-}
 
 namespace ImageUtils {