diff --git a/change_notes/2023-11-07-use-misra-underlying-type.md b/change_notes/2023-11-07-use-misra-underlying-type.md
new file mode 100644
index 0000000000..e322e8c2dd
--- /dev/null
+++ b/change_notes/2023-11-07-use-misra-underlying-type.md
@@ -0,0 +1,2 @@
+- `M5-0-20` - `BitwiseOperatorOperandsHaveDifferentUnderlyingType.ql`:
+  - Use the Misra definition of underlying type.
diff --git a/cpp/autosar/src/rules/M5-0-20/BitwiseOperatorOperandsHaveDifferentUnderlyingType.ql b/cpp/autosar/src/rules/M5-0-20/BitwiseOperatorOperandsHaveDifferentUnderlyingType.ql
index d400faf0c1..7951f98bd5 100644
--- a/cpp/autosar/src/rules/M5-0-20/BitwiseOperatorOperandsHaveDifferentUnderlyingType.ql
+++ b/cpp/autosar/src/rules/M5-0-20/BitwiseOperatorOperandsHaveDifferentUnderlyingType.ql
@@ -17,6 +17,7 @@
 import cpp
 import codingstandards.cpp.autosar
 import codingstandards.cpp.Bitwise
+import codingstandards.cpp.Conversion
 
 predicate isBinaryBitwiseOperation(Operation o, VariableAccess l, VariableAccess r) {
   exists(BinaryBitwiseOperation bbo | bbo = o |
@@ -29,10 +30,14 @@ predicate isBinaryBitwiseOperation(Operation o, VariableAccess l, VariableAccess
   )
 }
 
-from Operation o, Variable left, Variable right
+from
+  Operation o, VariableAccess left, VariableAccess right, Type leftUnderlyingType, Type rightUnderlyingType
 where
   not isExcluded(o, ExpressionsPackage::bitwiseOperatorOperandsHaveDifferentUnderlyingTypeQuery()) and
   not o.isFromUninstantiatedTemplate(_) and
-  isBinaryBitwiseOperation(o, left.getAnAccess(), right.getAnAccess()) and
-  left.getUnderlyingType() != right.getUnderlyingType()
-select o, "Operands of the '" + o.getOperator() + "' operation have different underlying types."
+  isBinaryBitwiseOperation(o, left, right) and
+  leftUnderlyingType = MisraConversion::getUnderlyingType(left) and
+  rightUnderlyingType = MisraConversion::getUnderlyingType(right) and
+  leftUnderlyingType != rightUnderlyingType
+select o,
+  "Operands of the '" + o.getOperator() + "' operation have different underlying types '" + leftUnderlyingType.getName() + "' and '" + rightUnderlyingType.getName() + "'."
diff --git a/cpp/autosar/test/rules/M5-0-20/BitwiseOperatorOperandsHaveDifferentUnderlyingType.expected b/cpp/autosar/test/rules/M5-0-20/BitwiseOperatorOperandsHaveDifferentUnderlyingType.expected
index ac31001f57..806c82599d 100644
--- a/cpp/autosar/test/rules/M5-0-20/BitwiseOperatorOperandsHaveDifferentUnderlyingType.expected
+++ b/cpp/autosar/test/rules/M5-0-20/BitwiseOperatorOperandsHaveDifferentUnderlyingType.expected
@@ -1,21 +1,21 @@
-| test.cpp:18:3:18:6 | ... & ... | Operands of the '&' operation have different underlying types. |
-| test.cpp:19:3:19:7 | ... \| ... | Operands of the '\|' operation have different underlying types. |
-| test.cpp:20:3:20:7 | ... ^ ... | Operands of the '^' operation have different underlying types. |
-| test.cpp:21:3:21:8 | ... << ... | Operands of the '<<' operation have different underlying types. |
-| test.cpp:22:3:22:8 | ... >> ... | Operands of the '>>' operation have different underlying types. |
-| test.cpp:23:3:23:8 | ... &= ... | Operands of the '&=' operation have different underlying types. |
-| test.cpp:24:3:24:8 | ... \|= ... | Operands of the '\|=' operation have different underlying types. |
-| test.cpp:25:3:25:8 | ... ^= ... | Operands of the '^=' operation have different underlying types. |
-| test.cpp:26:3:26:9 | ... <<= ... | Operands of the '<<=' operation have different underlying types. |
-| test.cpp:27:3:27:9 | ... >>= ... | Operands of the '>>=' operation have different underlying types. |
-| test.cpp:45:3:45:6 | ... & ... | Operands of the '&' operation have different underlying types. |
-| test.cpp:46:3:46:7 | ... \| ... | Operands of the '\|' operation have different underlying types. |
-| test.cpp:47:3:47:7 | ... ^ ... | Operands of the '^' operation have different underlying types. |
-| test.cpp:48:3:48:8 | ... << ... | Operands of the '<<' operation have different underlying types. |
-| test.cpp:49:3:49:8 | ... >> ... | Operands of the '>>' operation have different underlying types. |
-| test.cpp:50:3:50:8 | ... &= ... | Operands of the '&=' operation have different underlying types. |
-| test.cpp:51:3:51:8 | ... \|= ... | Operands of the '\|=' operation have different underlying types. |
-| test.cpp:52:3:52:8 | ... ^= ... | Operands of the '^=' operation have different underlying types. |
-| test.cpp:53:3:53:9 | ... <<= ... | Operands of the '<<=' operation have different underlying types. |
-| test.cpp:54:3:54:9 | ... >>= ... | Operands of the '>>=' operation have different underlying types. |
-| test.cpp:67:3:67:14 | ... << ... | Operands of the '<<' operation have different underlying types. |
+| test.cpp:18:3:18:6 | ... & ... | Operands of the '&' operation have different underlying types 'unsigned int' and 'unsigned short'. |
+| test.cpp:19:3:19:7 | ... \| ... | Operands of the '\|' operation have different underlying types 'unsigned int' and 'unsigned short'. |
+| test.cpp:20:3:20:7 | ... ^ ... | Operands of the '^' operation have different underlying types 'unsigned int' and 'unsigned short'. |
+| test.cpp:21:3:21:8 | ... << ... | Operands of the '<<' operation have different underlying types 'unsigned int' and 'unsigned short'. |
+| test.cpp:22:3:22:8 | ... >> ... | Operands of the '>>' operation have different underlying types 'unsigned int' and 'unsigned short'. |
+| test.cpp:23:3:23:8 | ... &= ... | Operands of the '&=' operation have different underlying types 'unsigned int' and 'unsigned short'. |
+| test.cpp:24:3:24:8 | ... \|= ... | Operands of the '\|=' operation have different underlying types 'unsigned int' and 'unsigned short'. |
+| test.cpp:25:3:25:8 | ... ^= ... | Operands of the '^=' operation have different underlying types 'unsigned int' and 'unsigned short'. |
+| test.cpp:26:3:26:9 | ... <<= ... | Operands of the '<<=' operation have different underlying types 'unsigned int' and 'unsigned short'. |
+| test.cpp:27:3:27:9 | ... >>= ... | Operands of the '>>=' operation have different underlying types 'unsigned int' and 'unsigned short'. |
+| test.cpp:45:3:45:6 | ... & ... | Operands of the '&' operation have different underlying types 'unsigned char' and 'unsigned short'. |
+| test.cpp:46:3:46:7 | ... \| ... | Operands of the '\|' operation have different underlying types 'unsigned char' and 'unsigned short'. |
+| test.cpp:47:3:47:7 | ... ^ ... | Operands of the '^' operation have different underlying types 'unsigned char' and 'unsigned short'. |
+| test.cpp:48:3:48:8 | ... << ... | Operands of the '<<' operation have different underlying types 'unsigned char' and 'unsigned short'. |
+| test.cpp:49:3:49:8 | ... >> ... | Operands of the '>>' operation have different underlying types 'unsigned char' and 'unsigned short'. |
+| test.cpp:50:3:50:8 | ... &= ... | Operands of the '&=' operation have different underlying types 'unsigned char' and 'unsigned short'. |
+| test.cpp:51:3:51:8 | ... \|= ... | Operands of the '\|=' operation have different underlying types 'unsigned char' and 'unsigned short'. |
+| test.cpp:52:3:52:8 | ... ^= ... | Operands of the '^=' operation have different underlying types 'unsigned char' and 'unsigned short'. |
+| test.cpp:53:3:53:9 | ... <<= ... | Operands of the '<<=' operation have different underlying types 'unsigned char' and 'unsigned short'. |
+| test.cpp:54:3:54:9 | ... >>= ... | Operands of the '>>=' operation have different underlying types 'unsigned char' and 'unsigned short'. |
+| test.cpp:67:3:67:14 | ... << ... | Operands of the '<<' operation have different underlying types 'int &' and 'char &'. |