diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index d961a9f6e..cf5303a2c 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/testtokenize.cpp b/test/testtokenize.cpp
index af455a0cf..6dcf245be 100644
--- a/test/testtokenize.cpp
+++ b/test/testtokenize.cpp
@@ -6936,6 +6936,14 @@ 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.");
     }