diff --git a/lib/symboldatabase.cpp b/lib/symboldatabase.cpp
index 35ca24485..5a8e23011 100644
--- a/lib/symboldatabase.cpp
+++ b/lib/symboldatabase.cpp
@@ -206,7 +206,7 @@ SymbolDatabase::SymbolDatabase(const Tokenizer *tokenizer, const Settings *setti
         }
 
         // using namespace
-        else if (Token::Match(tok, "using namespace ::| %type% ;|::")) {
+        else if (_tokenizer->isCPP() && Token::Match(tok, "using namespace ::| %type% ;|::")) {
             Scope::UsingInfo using_info;
 
             using_info.start = tok; // save location
@@ -622,7 +622,7 @@ SymbolDatabase::SymbolDatabase(const Tokenizer *tokenizer, const Settings *setti
                 }
 
                 // friend class declaration?
-                else if (Token::Match(tok, "friend class| ::| %any% ;|::")) {
+                else if (_tokenizer->isCPP() && Token::Match(tok, "friend class| ::| %any% ;|::")) {
                     Type::FriendInfo friendInfo;
 
                     // save the name start
@@ -644,6 +644,10 @@ SymbolDatabase::SymbolDatabase(const Tokenizer *tokenizer, const Settings *setti
                     // fill this in after parsing is complete
                     friendInfo.type = 0;
 
+                    if (!scope->definedType) {
+                        _tokenizer->syntaxError(tok);
+                        return;
+                    }
                     scope->definedType->friendList.push_back(friendInfo);
                 }
             } else if (scope->type == Scope::eNamespace || scope->type == Scope::eGlobal) {
diff --git a/test/testgarbage.cpp b/test/testgarbage.cpp
index 32032197a..bd7bf9cd0 100644
--- a/test/testgarbage.cpp
+++ b/test/testgarbage.cpp
@@ -121,6 +121,7 @@ private:
         TEST_CASE(garbageCode80);
         TEST_CASE(garbageCode81);
         TEST_CASE(garbageCode82);
+        TEST_CASE(garbageCode83);
 
         TEST_CASE(garbageValueFlow);
         TEST_CASE(garbageSymbolDatabase);
@@ -671,6 +672,10 @@ private:
         ASSERT_THROW(checkCode("p(\"Hello \" 14) _yn(const size_t) typedef bool pfunk (*pfunk)(const size_t)"), InternalError);
     }
 
+    void garbageCode83() { // #6771
+        ASSERT_THROW(checkCode("namespace A { class } class A { friend C ; } { } ;"), InternalError);
+    }
+
     void garbageValueFlow() {
         // #6089
         const char* code = "{} int foo(struct, x1, struct x2, x3, int, x5, x6, x7)\n"