diff --git a/lib/astutils.cpp b/lib/astutils.cpp
index 0d9b6b78bca..0818086b0ec 100644
--- a/lib/astutils.cpp
+++ b/lib/astutils.cpp
@@ -1455,7 +1455,7 @@ bool isUsedAsBool(const Token* const tok, const Settings* settings)
         return isUsedAsBool(parent);
     if (parent->isUnaryOp("*"))
         return isUsedAsBool(parent);
-    if (Token::Match(parent, "==|!=") && tok->astSibling()->hasKnownIntValue() &&
+    if (Token::Match(parent, "==|!=") && (tok->astSibling()->isNumber() || tok->astSibling()->isLiteral()) && tok->astSibling()->hasKnownIntValue() &&
         tok->astSibling()->values().front().intvalue == 0)
         return true;
     if (parent->str() == "(" && astIsRHS(tok) && Token::Match(parent->astOperand1(), "if|while"))
diff --git a/test/testcondition.cpp b/test/testcondition.cpp
index 9db2ab90704..7073d4a9cff 100644
--- a/test/testcondition.cpp
+++ b/test/testcondition.cpp
@@ -3550,6 +3550,13 @@ class TestCondition : public TestFixture {
               "}");
         ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (warning) Identical condition 'handle!=0', second condition is always false\n", errout.str());
 
+        check("int f(void *handle) {\n"
+              "    if (handle != nullptr) return 0;\n"
+              "    if (handle) return 1;\n"
+              "    else return 0;\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (warning) Identical condition 'handle!=0', second condition is always false\n", errout.str());
+
         check("void f(void* x, void* y) {\n"
               "    if (x == nullptr && y == nullptr)\n"
               "        return;\n"
diff --git a/test/teststring.cpp b/test/teststring.cpp
index 05e88abd135..e94f969034d 100644
--- a/test/teststring.cpp
+++ b/test/teststring.cpp
@@ -792,6 +792,13 @@ class TestString : public TestFixture {
               "    g(2, !\"def\");\n"
               "}\n");
         ASSERT_EQUALS("[test.cpp:4]: (warning) Conversion of string literal \"def\" to bool always evaluates to true.\n", errout.str());
+
+        check("bool f(const char *p) {\n"
+              "    if (*p == '\\0')\n"
+              "        return *p == '\\0';\n"
+              "    return false;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void deadStrcmp() {