diff --git a/addons/misra-test.c b/addons/misra-test.c
index 51bf8f238..ece5e4540 100644
--- a/addons/misra-test.c
+++ b/addons/misra-test.c
@@ -196,3 +196,6 @@ void misra_18_8(int x) {
 union misra_19_2 { }; // 19.2
 
 #include "notfound.h" // 20.1
+
+#define int short // 20.4
+#undef X  // 20.5
diff --git a/addons/misra.py b/addons/misra.py
index 2745eea63..5cd3382ab 100644
--- a/addons/misra.py
+++ b/addons/misra.py
@@ -633,6 +633,14 @@ def misra_20_4(rawTokens):
         if macroName in KEYWORDS:
             reportError(token, 20, 4)
 
+def misra_20_5(rawTokens):
+    linenr = -1
+    for token in rawTokens:
+        if token.str.startswith('/') or token.linenr == linenr:
+            continue
+        linenr = token.linenr
+        if simpleMatch(token, '# undef'):
+            reportError(token, 20, 5)
 
 if '-verify' in sys.argv[1:]:
     VERIFY = True
@@ -703,6 +711,8 @@ for arg in sys.argv[1:]:
             misra_20_1(data.rawTokens)
             misra_20_2(data.rawTokens)
             misra_20_3(data.rawTokens)
+            misra_20_4(data.rawTokens)
+            misra_20_5(data.rawTokens)
 
     if VERIFY:
         for expected in VERIFY_EXPECTED: