diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index 00a39e76d..636215114 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -8106,6 +8106,8 @@ void Tokenizer::reportUnknownMacros() const
                 else
                     unknownMacroError(tok);
             }
+        } else if (isCPP() && Token::Match(tok, "public|private|protected %name% :")) {
+            unknownMacroError(tok->next());
         }
     }
 
diff --git a/test/teststl.cpp b/test/teststl.cpp
index cc8ba3168..c7e28d283 100644
--- a/test/teststl.cpp
+++ b/test/teststl.cpp
@@ -5513,7 +5513,7 @@ private:
               "    QString s;\n"
               "public:\n"
               "    C(QString);\n"
-              "private slots:\n"
+              "private:\n"
               "    void f() {\n"
               "        QVERIFY(QDir(s).exists());\n"
               "    }\n"
diff --git a/test/testsymboldatabase.cpp b/test/testsymboldatabase.cpp
index 6c664e169..159c4a7e9 100644
--- a/test/testsymboldatabase.cpp
+++ b/test/testsymboldatabase.cpp
@@ -2859,7 +2859,7 @@ private:
 
     void symboldatabase2() {
         check("class foo {\n"
-              "public slots :\n"
+              "public:\n"
               "foo() { }\n"
               "};");
         ASSERT_EQUALS("", errout.str());
diff --git a/test/testtokenize.cpp b/test/testtokenize.cpp
index af455a0cf..2d00e507f 100644
--- a/test/testtokenize.cpp
+++ b/test/testtokenize.cpp
@@ -6936,6 +6936,21 @@ private:
         ASSERT_THROW_EQUALS(tokenizeAndStringify("int f() { MACRO(x) return 0; }"),
                             InternalError,
                             "There is an unknown macro here somewhere. Configuration is required. If MACRO is a macro then please configure it.");
+
+        ASSERT_THROW_EQUALS(tokenizeAndStringify("class C : public QObject {\n" // #11770
+                                                 "    struct S { static void g() {} };\n"
+                                                 "private Q_SLOTS:\n"
+                                                 "    void f() { S::g(); }\n"
+                                                 "};\n"),
+                            InternalError,
+                            "There is an unknown macro here somewhere. Configuration is required. If Q_SLOTS is a macro then please configure it.");
+        ASSERT_THROW_EQUALS(tokenizeAndStringify("class C : public QObject {\n"
+                                                 "    struct S { static void g() {} };\n"
+                                                 "private slots:\n"
+                                                 "    void f() { S::g(); }\n"
+                                                 "};\n"),
+                            InternalError,
+                            "There is an unknown macro here somewhere. Configuration is required. If slots is a macro then please configure it.");
     }
 
 
diff --git a/test/testvalueflow.cpp b/test/testvalueflow.cpp
index 6e36c1896..1645a92cf 100644
--- a/test/testvalueflow.cpp
+++ b/test/testvalueflow.cpp
@@ -7074,7 +7074,7 @@ private:
         valueOfTok(code, "c");
 
         code = "class T {\n"
-               "private slots:\n"
+               "private:\n"
                "    void f() { D& r = dynamic_cast<D&>(*m); }\n"
                "    void g() { m.reset(new D); }\n"
                "private:\n"