diff --git a/esphome/components/modbus/modbus.cpp b/esphome/components/modbus/modbus.cpp
index 19b5e8019e..0928b0f6f3 100644
--- a/esphome/components/modbus/modbus.cpp
+++ b/esphome/components/modbus/modbus.cpp
@@ -76,7 +76,12 @@ bool Modbus::parse_modbus_byte_(uint8_t byte) {
     // installed, but wait, there is the CRC, and if we get a hit there is a good
     // chance that this is a complete message ... admittedly there is a small chance is
     // isn't but that is quite small given the purpose of the CRC in the first place
-    data_len = at;
+
+    // Fewer than 2 bytes can't calc CRC
+    if (at < 2)
+      return true;
+
+    data_len = at - 2;
     data_offset = 1;
 
     uint16_t computed_crc = crc16(raw, data_offset + data_len);