diff --git a/lib/astutils.cpp b/lib/astutils.cpp
index 462e862b5..8eec9f04c 100644
--- a/lib/astutils.cpp
+++ b/lib/astutils.cpp
@@ -1467,7 +1467,7 @@ bool isUsedAsBool(const Token* const tok, const Settings* settings)
     if (Token::Match(parent, "&&|!|%oror%"))
         return true;
     if (parent->isCast())
-        return isUsedAsBool(parent);
+        return !Token::simpleMatch(parent->astOperand1(), "dynamic_cast") && isUsedAsBool(parent);
     if (parent->isUnaryOp("*"))
         return isUsedAsBool(parent);
     if (Token::Match(parent, "==|!=") && (tok->astSibling()->isNumber() || tok->astSibling()->isKeyword()) && tok->astSibling()->hasKnownIntValue() &&
diff --git a/test/testother.cpp b/test/testother.cpp
index 6ad27e8e5..d6dfc0d63 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -11460,6 +11460,15 @@ private:
               "    return A{x};\n"
               "}\n");
         ASSERT_EQUALS("[test.cpp:4]: (style) Pointer expression 'x' converted to bool is always false.\n", errout.str());
+
+        check("struct B { virtual void f() {} };\n" // #11929
+              "struct D : B {};\n"
+              "void g(B* b) {\n"
+              "    if (!b)\n"
+              "        return;\n"
+              "    if (dynamic_cast<D*>(b)) {}\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 };