diff --git a/backend/genesys/gl841.cpp b/backend/genesys/gl841.cpp
index c1484fc3c..99e146322 100644
--- a/backend/genesys/gl841.cpp
+++ b/backend/genesys/gl841.cpp
@@ -753,11 +753,11 @@ static void gl841_init_motor_regs_scan(Genesys_Device* dev, const Genesys_Sensor
 	    fast_exposure / 4 *
         (feed_steps - fast_table.table.size()*2 -
          (slow_table.table.size() >> static_cast<unsigned>(motor_profile.step_type)))
-        + fast_table.pixeltime_sum*2 + slow_table.pixeltime_sum;
+        + fast_table.pixeltime_sum() * 2 + slow_table.pixeltime_sum();
 	slow_time =
 	    (scan_exposure_time * scan_yres) / dev->motor.base_ydpi *
         (feed_steps - (slow_table.table.size() >> static_cast<unsigned>(motor_profile.step_type)))
-        + slow_table.pixeltime_sum;
+        + slow_table.pixeltime_sum();
 
         use_fast_fed = fast_time < slow_time;
     }
diff --git a/backend/genesys/motor.cpp b/backend/genesys/motor.cpp
index 725035299..b0436c695 100644
--- a/backend/genesys/motor.cpp
+++ b/backend/genesys/motor.cpp
@@ -46,6 +46,7 @@
 #include "motor.h"
 #include "utilities.h"
 #include <cmath>
+#include <numeric>
 
 namespace genesys {
 
@@ -86,6 +87,7 @@ void MotorSlopeTable::slice_steps(unsigned count)
         throw SaneException("Excessive steps count");
     }
     table.resize(count);
+    generate_pixeltime_sum();
 }
 
 void MotorSlopeTable::expand_table(unsigned count)
@@ -94,6 +96,13 @@ void MotorSlopeTable::expand_table(unsigned count)
         throw SaneException("Can't expand empty table");
     }
     table.resize(table.size() + count, table.back());
+    generate_pixeltime_sum();
+}
+
+void MotorSlopeTable::generate_pixeltime_sum()
+{
+    pixeltime_sum_ = std::accumulate(table.begin(), table.end(),
+                                     std::size_t{0}, std::plus<std::size_t>());
 }
 
 unsigned get_slope_table_max_size(AsicType asic_type)
@@ -139,22 +148,21 @@ MotorSlopeTable create_slope_table_for_speed(const MotorSlope& slope, unsigned t
             break;
         }
         table.table.push_back(current);
-        table.pixeltime_sum += current;
     }
 
     // make sure the target speed (or the max speed if target speed is too high) is present in
     // the table
     table.table.push_back(final_speed);
-    table.pixeltime_sum += table.table.back();
 
     // fill the table up to the specified size
     while (table.table.size() < max_size - 1 &&
            (table.table.size() % steps_alignment != 0 || table.table.size() < min_size))
     {
         table.table.push_back(table.table.back());
-        table.pixeltime_sum += table.table.back();
     }
 
+    table.generate_pixeltime_sum();
+
     return table;
 }
 
diff --git a/backend/genesys/motor.h b/backend/genesys/motor.h
index 9473a79f0..1ffc1d8f3 100644
--- a/backend/genesys/motor.h
+++ b/backend/genesys/motor.h
@@ -126,12 +126,17 @@ struct MotorSlope
 struct MotorSlopeTable
 {
     std::vector<std::uint16_t> table;
-    unsigned pixeltime_sum = 0;
 
     void slice_steps(unsigned count);
 
     // expands the table by the given number of steps
     void expand_table(unsigned count);
+
+    std::uint64_t pixeltime_sum() const { return pixeltime_sum_; }
+
+    void generate_pixeltime_sum();
+private:
+    std::uint64_t pixeltime_sum_ = 0;
 };
 
 unsigned get_slope_table_max_size(AsicType asic_type);
diff --git a/testsuite/backend/genesys/tests_motor.cpp b/testsuite/backend/genesys/tests_motor.cpp
index dbe0ab704..ba982354d 100644
--- a/testsuite/backend/genesys/tests_motor.cpp
+++ b/testsuite/backend/genesys/tests_motor.cpp
@@ -46,7 +46,7 @@ void test_create_slope_table3()
     auto table = sanei_genesys_create_slope_table3(asic_type, motor, StepType::FULL, 10000,
                                                    motor.base_ydpi);
 
-    ASSERT_EQ(table.pixeltime_sum, 10000u);
+    ASSERT_EQ(table.pixeltime_sum(), 10000u);
     ASSERT_EQ(table.table.size(), 1u);
 
     std::vector<std::uint16_t> expected_steps = {
@@ -57,7 +57,7 @@ void test_create_slope_table3()
     table = sanei_genesys_create_slope_table3(asic_type, motor, StepType::FULL, 2000,
                                               motor.base_ydpi);
 
-    ASSERT_EQ(table.pixeltime_sum, 33830u);
+    ASSERT_EQ(table.pixeltime_sum(), 33830u);
     ASSERT_EQ(table.table.size(), 7u);
 
     expected_steps = {
@@ -68,7 +68,7 @@ void test_create_slope_table3()
     table = sanei_genesys_create_slope_table3(asic_type, motor, StepType::HALF, 10000,
                                               motor.base_ydpi);
 
-    ASSERT_EQ(table.pixeltime_sum, 5000u);
+    ASSERT_EQ(table.pixeltime_sum(), 5000u);
     ASSERT_EQ(table.table.size(), 1u);
 
     expected_steps = {
@@ -79,7 +79,7 @@ void test_create_slope_table3()
     table = sanei_genesys_create_slope_table3(asic_type, motor, StepType::HALF, 2000,
                                               motor.base_ydpi);
 
-    ASSERT_EQ(table.pixeltime_sum, 16914u);
+    ASSERT_EQ(table.pixeltime_sum(), 16914u);
     ASSERT_EQ(table.table.size(), 7u);
 
     expected_steps = {
@@ -90,7 +90,7 @@ void test_create_slope_table3()
     table = sanei_genesys_create_slope_table3(asic_type, motor, StepType::QUARTER, 10000,
                                               motor.base_ydpi);
 
-    ASSERT_EQ(table.pixeltime_sum, 2500u);
+    ASSERT_EQ(table.pixeltime_sum(), 2500u);
     ASSERT_EQ(table.table.size(), 1u);
 
     expected_steps = {
@@ -101,7 +101,7 @@ void test_create_slope_table3()
     table = sanei_genesys_create_slope_table3(asic_type, motor, StepType::QUARTER, 2000,
                                               motor.base_ydpi);
 
-    ASSERT_EQ(table.pixeltime_sum, 7680u);
+    ASSERT_EQ(table.pixeltime_sum(), 7680u);
     ASSERT_EQ(table.table.size(), 6u);
 
     expected_steps = {
@@ -127,7 +127,7 @@ void test_create_slope_table_small_full_step()
     };
     ASSERT_EQ(table.table, expected_table);
     ASSERT_EQ(table.table.size(), 8u);
-    ASSERT_EQ(table.pixeltime_sum, 156348u);
+    ASSERT_EQ(table.pixeltime_sum(), 156348u);
 
 
     table = create_slope_table_for_speed(slope, 3000, StepType::FULL, 4, 8, max_table_size);
@@ -137,7 +137,7 @@ void test_create_slope_table_small_full_step()
     };
     ASSERT_EQ(table.table, expected_table);
     ASSERT_EQ(table.table.size(), 8u);
-    ASSERT_EQ(table.pixeltime_sum, 148843u);
+    ASSERT_EQ(table.pixeltime_sum(), 148843u);
 }
 
 void test_create_slope_table_small_full_step_target_speed_too_high()
@@ -157,7 +157,7 @@ void test_create_slope_table_small_full_step_target_speed_too_high()
     };
     ASSERT_EQ(table.table, expected_table);
     ASSERT_EQ(table.table.size(), 8u);
-    ASSERT_EQ(table.pixeltime_sum, 148358u);
+    ASSERT_EQ(table.pixeltime_sum(), 148358u);
 }
 
 void test_create_slope_table_small_half_step()
@@ -177,7 +177,7 @@ void test_create_slope_table_small_half_step()
     };
     ASSERT_EQ(table.table, expected_table);
     ASSERT_EQ(table.table.size(), 8u);
-    ASSERT_EQ(table.pixeltime_sum, 78174u);
+    ASSERT_EQ(table.pixeltime_sum(), 78174u);
 
 
     table = create_slope_table_for_speed(slope, 3000, StepType::HALF, 4, 8, max_table_size);
@@ -187,7 +187,7 @@ void test_create_slope_table_small_half_step()
     };
     ASSERT_EQ(table.table, expected_table);
     ASSERT_EQ(table.table.size(), 8u);
-    ASSERT_EQ(table.pixeltime_sum, 74421u);
+    ASSERT_EQ(table.pixeltime_sum(), 74421u);
 }
 
 void test_create_slope_table_large_full_step()
@@ -235,7 +235,7 @@ void test_create_slope_table_large_full_step()
     };
     ASSERT_EQ(table.table, expected_table);
     ASSERT_EQ(table.table.size(), 60u);
-    ASSERT_EQ(table.pixeltime_sum, 412616u);
+    ASSERT_EQ(table.pixeltime_sum(), 412616u);
 
 
     table = create_slope_table_for_speed(slope, 1500, StepType::FULL, 4, 8, max_table_size);
@@ -267,7 +267,7 @@ void test_create_slope_table_large_full_step()
     };
     ASSERT_EQ(table.table, expected_table);
     ASSERT_EQ(table.table.size(), 224u);
-    ASSERT_EQ(table.pixeltime_sum, 734910u);
+    ASSERT_EQ(table.pixeltime_sum(), 734910u);
 }
 
 void test_create_slope_table_large_half_step()
@@ -293,7 +293,7 @@ void test_create_slope_table_large_half_step()
     };
     ASSERT_EQ(table.table, expected_table);
     ASSERT_EQ(table.table.size(), 60u);
-    ASSERT_EQ(table.pixeltime_sum, 206294u);
+    ASSERT_EQ(table.pixeltime_sum(), 206294u);
 
 
     table = create_slope_table_for_speed(slope, 1500, StepType::HALF, 4, 8, max_table_size);
@@ -325,7 +325,7 @@ void test_create_slope_table_large_half_step()
     };
     ASSERT_EQ(table.table, expected_table);
     ASSERT_EQ(table.table.size(), 224u);
-    ASSERT_EQ(table.pixeltime_sum, 367399u);
+    ASSERT_EQ(table.pixeltime_sum(), 367399u);
 }
 
 void test_motor()