diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index c1fbef34a..86ef750b3 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -4260,6 +4260,8 @@ void Tokenizer::simplifyFlowControl()
                        (Token::Match(tok->previous(), "[;{}] %name% (") &&
                         _settings->library.isnoreturn(tok)) ||
                        (isCPP() && tok->str() == "throw")) {
+                if (tok->next() == "}")
+                    syntaxError(tok->next()); // invalid code like in #6731
                 //TODO: ensure that we exclude user-defined 'exit|abort|throw', except for 'noreturn'
                 //catch the first ';'
                 for (Token *tok2 = tok->next(); tok2; tok2 = tok2->next()) {
@@ -4270,7 +4272,7 @@ void Tokenizer::simplifyFlowControl()
                         eraseDeadCode(tok, 0);
                         break;
                     } else if (Token::Match(tok2, "[{}]"))
-                        break;  //Wrong code.
+                        break;
                 }
                 //if everything is removed, then remove also the code after an inferior scope
                 //only if the actual scope is not special
diff --git a/test/testgarbage.cpp b/test/testgarbage.cpp
index e9f905642..18c1322f5 100644
--- a/test/testgarbage.cpp
+++ b/test/testgarbage.cpp
@@ -217,6 +217,7 @@ private:
         TEST_CASE(garbageCode166); // #7236
         TEST_CASE(garbageCode167); // #7237
         TEST_CASE(garbageCode168); // #7246
+        TEST_CASE(garbageCode169); // #6731
         TEST_CASE(garbageValueFlow);
         TEST_CASE(garbageSymbolDatabase);
         TEST_CASE(garbageAST);
@@ -965,11 +966,11 @@ private:
     }
 
     void garbageCode123() {
-        checkCode("namespace pr16989 {\n"
-                  "    class C {\n"
-                  "        C tpl_mem(T *) { return }\n"
-                  "    };\n"
-                  "}");
+        ASSERT_THROW(checkCode("namespace pr16989 {\n"
+                               "    class C {\n"
+                               "        C tpl_mem(T *) { return }\n"
+                               "    };\n"
+                               "}"), InternalError);
     }
 
     void garbageCode124() {
@@ -1429,6 +1430,12 @@ private:
         checkCode("long foo(void) { return *bar; }", false);
     }
 
+    void garbageCode169() {
+        // 6713
+        ASSERT_THROW(checkCode("( ) { ( ) ; { return } switch ( ) i\n"
+                               "set case break ; default: ( ) }", false), InternalError);
+    }
+
 };
 
 REGISTER_TEST(TestGarbage)