diff --git a/lib/valueflow.cpp b/lib/valueflow.cpp
index ffd9c209517..c650e12b65b 100644
--- a/lib/valueflow.cpp
+++ b/lib/valueflow.cpp
@@ -8707,10 +8707,12 @@ static MathLib::bigint valueFlowGetStrLength(const Token* tok)
         return Token::getStrLength(tok);
     if (astIsGenericChar(tok) || tok->tokType() == Token::eChar)
         return 1;
-    if (const ValueFlow::Value* v2 = tok->getKnownValue(ValueFlow::Value::ValueType::CONTAINER_SIZE))
-        return v2->intvalue;
-    if (const ValueFlow::Value* v1 = tok->getKnownValue(ValueFlow::Value::ValueType::TOK))
-        return valueFlowGetStrLength(v1->tokvalue);
+    if (const ValueFlow::Value* v = tok->getKnownValue(ValueFlow::Value::ValueType::CONTAINER_SIZE))
+        return v->intvalue;
+    if (const ValueFlow::Value* v = tok->getKnownValue(ValueFlow::Value::ValueType::TOK)) {
+        if (v->tokvalue != tok)
+            return valueFlowGetStrLength(v->tokvalue);
+    }
     return 0;
 }
 
diff --git a/test/testvalueflow.cpp b/test/testvalueflow.cpp
index f24942164fa..8a075721a84 100644
--- a/test/testvalueflow.cpp
+++ b/test/testvalueflow.cpp
@@ -7397,6 +7397,18 @@ class TestValueFlow : public TestFixture {
                "    }\n"
                "}";
         valueOfTok(code, "path");
+
+        code = "struct S {\n"
+               "    std::string to_string() const {\n"
+               "        return { this->p , (size_t)this->n };\n"
+               "    }\n"
+               "    const char* p;\n"
+               "    int n;\n"
+               "};\n"
+               "void f(S s, std::string& str) {\n"
+               "    str += s.to_string();\n"
+               "}\n";
+        valueOfTok(code, "s");
     }
 
     void valueFlowUnknownMixedOperators() {