diff --git a/bundles/org.openhab.binding.modbus/src/main/java/org/openhab/binding/modbus/internal/handler/ModbusDataThingHandler.java b/bundles/org.openhab.binding.modbus/src/main/java/org/openhab/binding/modbus/internal/handler/ModbusDataThingHandler.java
index 02328229d55a2..679aa68d61da2 100644
--- a/bundles/org.openhab.binding.modbus/src/main/java/org/openhab/binding/modbus/internal/handler/ModbusDataThingHandler.java
+++ b/bundles/org.openhab.binding.modbus/src/main/java/org/openhab/binding/modbus/internal/handler/ModbusDataThingHandler.java
@@ -631,7 +631,7 @@ private void validateReadIndex() throws ModbusConfigurationException {
 
         // Determine bit positions polled, both start and end inclusive
         int pollStartBitIndex = readRequest.getReference() * dataElementBits;
-        int pollEndBitIndex = pollStartBitIndex + readRequest.getDataLength() * dataElementBits;
+        int pollEndBitIndex = pollStartBitIndex + readRequest.getDataLength() * dataElementBits - 1;
 
         // Determine bit positions read, both start and end inclusive
         int readStartBitIndex = readIndex.get() * dataElementBits + readSubIndex.orElse(0) * valueTypeBitCount;
diff --git a/itests/org.openhab.binding.modbus.tests/src/main/java/org/openhab/binding/modbus/tests/ModbusDataHandlerTest.java b/itests/org.openhab.binding.modbus.tests/src/main/java/org/openhab/binding/modbus/tests/ModbusDataHandlerTest.java
index db2ff85c78349..8c5352ef298df 100644
--- a/itests/org.openhab.binding.modbus.tests/src/main/java/org/openhab/binding/modbus/tests/ModbusDataHandlerTest.java
+++ b/itests/org.openhab.binding.modbus.tests/src/main/java/org/openhab/binding/modbus/tests/ModbusDataHandlerTest.java
@@ -293,8 +293,16 @@ public void testInitCoilsOutOfIndex() {
                 ThingStatus.OFFLINE);
     }
 
+    @Test
+    public void testInitCoilsOutOfIndex2() {
+        // Reading coils 4, 5, 6. Coil 7 is out of bounds
+        testOutOfBoundsGeneric(4, 3, "7", ModbusReadFunctionCode.READ_COILS, ModbusConstants.ValueType.BIT,
+                ThingStatus.OFFLINE);
+    }
+
     @Test
     public void testInitCoilsOK() {
+        // Reading coils 4, 5, 6. Coil 6 is OK
         testOutOfBoundsGeneric(4, 3, "6", ModbusReadFunctionCode.READ_COILS, ModbusConstants.ValueType.BIT,
                 ThingStatus.ONLINE);
     }
@@ -349,12 +357,20 @@ public void testInitRegistersWithInt8OK2() {
 
     @Test
     public void testInitRegistersWithInt16OK() {
+        // Poller reading registers 4, 5, 6. Register 6 is OK
         testOutOfBoundsGeneric(4, 3, "6", ModbusReadFunctionCode.READ_MULTIPLE_REGISTERS,
                 ModbusConstants.ValueType.INT16, ThingStatus.ONLINE);
     }
 
     @Test
     public void testInitRegistersWithInt16OutOfBounds() {
+        // Poller reading registers 4, 5, 6. Register 7 is out-of-bounds
+        testOutOfBoundsGeneric(4, 3, "7", ModbusReadFunctionCode.READ_MULTIPLE_REGISTERS,
+                ModbusConstants.ValueType.INT16, ThingStatus.OFFLINE);
+    }
+
+    @Test
+    public void testInitRegistersWithInt16OutOfBounds2() {
         testOutOfBoundsGeneric(4, 3, "8", ModbusReadFunctionCode.READ_MULTIPLE_REGISTERS,
                 ModbusConstants.ValueType.INT16, ThingStatus.OFFLINE);
     }