diff --git a/backend/genesys/gl841.cpp b/backend/genesys/gl841.cpp
index 470f9ba..1c9cbe7 100644
--- a/backend/genesys/gl841.cpp
+++ b/backend/genesys/gl841.cpp
@@ -944,7 +944,7 @@ HOME_FREE: 3
         r->value |= REG_0x02_MTRREV;
     }
 
-    gl841_send_slope_table(dev, 3, fast_table.table, 256);
+    gl841_send_slope_table(dev, 3, fast_table.table, 255);
 
     r = sanei_genesys_get_address(reg, 0x67);
     r->value = 0x3f;
@@ -1165,18 +1165,18 @@ HOME_FREE: 3
         r->value &= ~0x40;
     }
 
-    gl841_send_slope_table(dev, 0, slow_table.table, 256);
+    gl841_send_slope_table(dev, 0, slow_table.table, 255);
 
-    gl841_send_slope_table(dev, 1, back_table.table, 256);
+    gl841_send_slope_table(dev, 1, back_table.table, 255);
 
-    gl841_send_slope_table(dev, 2, slow_table.table, 256);
+    gl841_send_slope_table(dev, 2, slow_table.table, 255);
 
     if (use_fast_fed) {
-        gl841_send_slope_table(dev, 3, fast_table.table, 256);
+        gl841_send_slope_table(dev, 3, fast_table.table, 255);
     }
 
     if (has_flag(flags, MotorFlag::AUTO_GO_HOME)) {
-        gl841_send_slope_table(dev, 4, fast_table.table, 256);
+        gl841_send_slope_table(dev, 4, fast_table.table, 255);
     }
 
 /* now reg 0x21 and 0x24 are available, we can calculate reg 0x22 and 0x23,