diff --git a/ChangeLog b/ChangeLog
index 5720d4bba7..6231170336 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2005-01-13  Bill Skaggs <weskaggs@primate.ucdavis.edu>
+
+	* plug-ins/bmp/bmp.h
+	* plug-ins/bmp/bmpread.c: handle negative height values
+	as per spec, fixes bug #158033
+	
 2005-01-13  Michael Natterer  <mitch@gimp.org>
 
 	Allow to easily open brushes and patterns as images.
diff --git a/plug-ins/bmp/bmp.h b/plug-ins/bmp/bmp.h
index 7270f3af35..0dc5d39512 100644
--- a/plug-ins/bmp/bmp.h
+++ b/plug-ins/bmp/bmp.h
@@ -46,7 +46,7 @@ extern struct Bitmap_File_Head_Struct
 extern struct Bitmap_Head_Struct
 {
   gulong   biWidth;     /* 12 */
-  gulong   biHeight;    /* 16 */
+  glong    biHeight;    /* 16 */
   gushort  biPlanes;    /* 1A */
   gushort  biBitCnt;    /* 1C */
   gulong   biCompr;     /* 1E */
diff --git a/plug-ins/bmp/bmpread.c b/plug-ins/bmp/bmpread.c
index e953eadb7d..c711398e8f 100644
--- a/plug-ins/bmp/bmpread.c
+++ b/plug-ins/bmp/bmpread.c
@@ -103,7 +103,7 @@ ReadChannelMasks (FILE *fd, Bitmap_Channel *masks, guint channels)
   guint32 tmp[3];
   guint32 mask;
   gint   i, nbits, offset, bit;
-  
+
   if (!ReadOK (fd, tmp, 3 * sizeof (guint32)))
     return FALSE;
 
@@ -167,8 +167,8 @@ ReadBMP (const gchar *name)
      !strncmp (magick,"PI",2) || !strncmp (magick,"CI",2)   ||
      !strncmp (magick,"CP",2)))
     {
-      g_message (_("'%s' is not a valid BMP file"),
-                 gimp_filename_to_utf8 (filename));
+      g_message (_("'%s' is not a valid BMP file 0, magick = %c%c"),
+                 gimp_filename_to_utf8 (filename), magick[0], magick[1]);
       return -1;
     }
 
@@ -176,13 +176,13 @@ ReadBMP (const gchar *name)
     {
       if (!ReadOK (fd, buffer, 12))
 	{
-          g_message (_("'%s' is not a valid BMP file"),
+          g_message (_("'%s' is not a valid BMP file 1"),
                       gimp_filename_to_utf8 (filename));
           return -1;
         }
       if (!ReadOK (fd, magick, 2))
 	{
-          g_message (_("'%s' is not a valid BMP file"),
+          g_message (_("'%s' is not a valid BMP file 2"),
                       gimp_filename_to_utf8 (filename));
           return -1;
         }
@@ -190,7 +190,7 @@ ReadBMP (const gchar *name)
 
   if (!ReadOK (fd, buffer, 12))
     {
-      g_message (_("'%s' is not a valid BMP file"),
+      g_message (_("'%s' is not a valid BMP file 3"),
                   gimp_filename_to_utf8 (filename));
       return -1;
     }
@@ -338,7 +338,7 @@ ReadBMP (const gchar *name)
       masks = g_new (Bitmap_Channel, 3);
       if (! ReadChannelMasks (fd, masks, 3))
         {
-          g_message (_("'%s' is not a valid BMP file"),
+          g_message (_("'%s' is not a valid BMP file 4"),
                       gimp_filename_to_utf8 (filename));
           return -1;
         }
@@ -374,7 +374,7 @@ ReadBMP (const gchar *name)
   /* Get the Image and return the ID or -1 on error*/
   image_ID = ReadImage (fd,
 			Bitmap_Head.biWidth,
-			Bitmap_Head.biHeight,
+			ABS (Bitmap_Head.biHeight),
 			ColorMap,
 			Bitmap_Head.biClrUsed,
 			Bitmap_Head.biBitCnt,
@@ -400,6 +400,9 @@ ReadBMP (const gchar *name)
       gimp_image_set_resolution (image_ID, xresolution, yresolution);
     }
 
+  if (Bitmap_Head.biHeight < 0)
+    gimp_image_flip (image_ID, GIMP_ORIENTATION_VERTICAL);
+
   return image_ID;
 }