diff --git a/lib/astutils.cpp b/lib/astutils.cpp
index c91f41d9651..922c734511a 100644
--- a/lib/astutils.cpp
+++ b/lib/astutils.cpp
@@ -1546,8 +1546,8 @@ bool isUsedAsBool(const Token* const tok, const Settings& settings)
         return !Token::simpleMatch(parent->astOperand1(), "dynamic_cast") && isUsedAsBool(parent, settings);
     if (parent->isUnaryOp("*"))
         return isUsedAsBool(parent, settings);
-    if (Token::Match(parent, "==|!=") && (tok->astSibling()->isNumber() || tok->astSibling()->isKeyword()) && tok->astSibling()->hasKnownIntValue() &&
-        tok->astSibling()->getKnownIntValue() == 0)
+    if (Token::Match(parent, "==|!=") && tok->valueType() && tok->valueType()->pointer &&
+        tok->astSibling()->hasKnownIntValue() && tok->astSibling()->getKnownIntValue() == 0)
         return true;
     if (parent->str() == "(" && astIsRHS(tok) && Token::Match(parent->astOperand1(), "if|while"))
         return true;
diff --git a/test/testcondition.cpp b/test/testcondition.cpp
index ffeca5c5be7..10eb92578cc 100644
--- a/test/testcondition.cpp
+++ b/test/testcondition.cpp
@@ -3640,6 +3640,15 @@ class TestCondition : public TestFixture {
               "}");
         ASSERT_EQUALS("[test.cpp:2:16] -> [test.cpp:3:9]: (warning) Identical condition 'handle!=nullptr', second condition is always false [identicalConditionAfterEarlyExit]\n", errout_str());
 
+        check("int f(const char* p) {\n" // #13717
+              "    if (p) {}\n"
+              "    else if (!p) {}\n"
+              "    else if (p == NULL) {}\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:2:9] -> [test.cpp:3:14]: (style) Expression is always true because 'else if' condition is opposite to previous condition at line 2. [multiCondition]\n"
+                      "[test.cpp:4:16]: (style) Expression is always false because 'else if' condition matches previous condition at line 3. [multiCondition]\n",
+                      errout_str());
+
         check("void f(void* x, void* y) {\n"
               "    if (x == nullptr && y == nullptr)\n"
               "        return;\n"