diff --git a/ChangeLog b/ChangeLog
index 3c99c2ba1..37e2a1c60 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2009-06-07  Werner Lemberg  <wl@gnu.org>
+
+	Simplify math.
+	Suggested by Alexei Podtelezhnikov <apodtele@gmail.com>.
+
+	* src/raster/ftraster.c (Vertical_Sweep_Drop, Horizontal_Sweep_Drop,
+	Horizontal_Gray_Sweep_Drop): Do it.
+
 2009-06-04  Werner Lemberg  <wl@gnu.org>
 
 	Preparation for fixing scan conversion rules 4 and 6.
diff --git a/src/raster/ftraster.c b/src/raster/ftraster.c
index 62b1a69e4..12a8dff3e 100644
--- a/src/raster/ftraster.c
+++ b/src/raster/ftraster.c
@@ -2229,7 +2229,7 @@
           break;
 
         case 4: /* smart drop-outs including stubs */
-          pxl = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half - 1 );
+          pxl = FLOOR( ( x1 + x2 - 1 ) / 2 + ras.precision_half );
           break;
 
         case 1: /* simple drop-outs excluding stubs */
@@ -2275,7 +2275,7 @@
           if ( ras.dropOutControl == 1 )
             pxl = e2;
           else
-            pxl = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half - 1 );
+            pxl = FLOOR( ( x1 + x2 - 1 ) / 2 + ras.precision_half );
           break;
 
         default: /* modes 2, 3, 6, 7 */
@@ -2424,7 +2424,7 @@
           break;
 
         case 4: /* smart drop-outs including stubs */
-          pxl = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half - 1 );
+          pxl = FLOOR( ( x1 + x2 - 1 ) / 2 + ras.precision_half );
           break;
 
         case 1: /* simple drop-outs excluding stubs */
@@ -2442,7 +2442,7 @@
           if ( ras.dropOutControl == 1 )
             pxl = e2;
           else
-            pxl = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half - 1 );
+            pxl = FLOOR( ( x1 + x2 - 1 ) / 2 + ras.precision_half );
           break;
 
         default: /* modes 2, 3, 6, 7 */
@@ -2674,7 +2674,7 @@
           break;
 
         case 4: /* smart drop-outs including stubs */
-          e1 = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half - 1 );
+          e1 = FLOOR( ( x1 + x2 - 1 ) / 2 + ras.precision_half );
           break;
 
         case 1: /* simple drop-outs excluding stubs */
@@ -2692,7 +2692,7 @@
           if ( ras.dropOutControl == 1 )
             e1 = e2;
           else
-            e1 = FLOOR( ( x1 + x2 + 1 ) / 2 + ras.precision_half - 1 );
+            e1 = FLOOR( ( x1 + x2 - 1 ) / 2 + ras.precision_half );
 
           break;