diff --git a/lib/checkclass.cpp b/lib/checkclass.cpp
index 1bf64d987..c66ab638c 100644
--- a/lib/checkclass.cpp
+++ b/lib/checkclass.cpp
@@ -1976,7 +1976,7 @@ bool CheckClass::checkConstFunc(const std::string &classname, const Var *varlist
         }
 
         // function call..
-        else if (tok1->str() != "return" && Token::Match(tok1, "%var% ("))
+        else if (tok1->str() != "return" && Token::Match(tok1, "%var% (") && tok1->str() != "c_str")
         {
             isconst = false;
             break;
diff --git a/test/testclass.cpp b/test/testclass.cpp
index 2b95edf6f..987aa257c 100644
--- a/test/testclass.cpp
+++ b/test/testclass.cpp
@@ -3451,7 +3451,7 @@ private:
                    "std::string m_strVal;\n"
                    "};\n"
                   );
-        TODO_ASSERT_EQUALS("[test.cpp:4]: (style) The function 'A::strGetString' can be const\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:4]: (style) The function 'A::strGetString' can be const\n", errout.str());
 
         checkConst("class A{\n"
                    "public:\n"
@@ -3462,7 +3462,7 @@ private:
                    "std::string m_strVal;\n"
                    "};\n"
                   );
-        TODO_ASSERT_EQUALS("[test.cpp:4]: (style) The function 'A::strGetString1' can be const\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:4]: (style) The function 'A::strGetString1' can be const\n", errout.str());
     }
 
     // increment/decrement => not const