diff --git a/components/freemodbus/common/esp_modbus_slave.c b/components/freemodbus/common/esp_modbus_slave.c
index a5b055860f..f69599c04a 100644
--- a/components/freemodbus/common/esp_modbus_slave.c
+++ b/components/freemodbus/common/esp_modbus_slave.c
@@ -62,7 +62,7 @@ static mb_descr_entry_t* mbc_slave_find_reg_descriptor(mb_param_type_t type, uin
         if ((addr >= it->start_offset)
             && (it->p_data)
             && (regs >= 1)
-            && ((addr + regs) <= (it->start_offset + reg_size + 1))
+            && ((addr + regs) <= (it->start_offset + reg_size))
             && (reg_size >= 1)) {
             return it;
         }
diff --git a/examples/protocols/modbus/serial/mb_slave/main/slave.c b/examples/protocols/modbus/serial/mb_slave/main/slave.c
index 0c0372bbe1..30f3a38580 100644
--- a/examples/protocols/modbus/serial/mb_slave/main/slave.c
+++ b/examples/protocols/modbus/serial/mb_slave/main/slave.c
@@ -118,7 +118,8 @@ void app_main(void)
     reg_area.type = MB_PARAM_HOLDING; // Set type of register area
     reg_area.start_offset = MB_REG_HOLDING_START_AREA0; // Offset of register area in Modbus protocol
     reg_area.address = (void*)&holding_reg_params.holding_data0; // Set pointer to storage instance
-    reg_area.size = sizeof(float) << 2; // Set the size of register storage instance
+    // Set the size of register storage instance = 150 holding registers
+    reg_area.size = (size_t)(HOLD_OFFSET(holding_data4) - HOLD_OFFSET(test_regs));
     ESP_ERROR_CHECK(mbc_slave_set_descriptor(reg_area));
     reg_area.type = MB_PARAM_HOLDING; // Set type of register area
     reg_area.start_offset = MB_REG_HOLDING_START_AREA1; // Offset of register area in Modbus protocol
@@ -132,7 +133,6 @@ void app_main(void)
     reg_area.address = (void*)&input_reg_params.input_data0;
     reg_area.size = sizeof(float) << 2;
     ESP_ERROR_CHECK(mbc_slave_set_descriptor(reg_area));
-    // Initialization of Input Registers area
     reg_area.type = MB_PARAM_INPUT;
     reg_area.start_offset = MB_REG_INPUT_START_AREA1;
     reg_area.address = (void*)&input_reg_params.input_data4;