diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index 67699d4cd..ba0ca8e01 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -2597,8 +2597,8 @@ void Tokenizer::setVarId()
             if (!scopeStack.top().isExecutable)
                 newFunctionDeclEnd = isFunctionHead(tok, "{:;");
             else {
-                Token const * tokenLinkNext = tok->link()->next();
-                if (tokenLinkNext->str() == "{") // might be for- or while-loop or if-statement
+                Token const * const tokenLinkNext = tok->link()->next();
+                if (tokenLinkNext && tokenLinkNext->str() == "{") // might be for- or while-loop or if-statement
                     newFunctionDeclEnd = tokenLinkNext;
             }
             if (newFunctionDeclEnd &&
diff --git a/test/testtokenize.cpp b/test/testtokenize.cpp
index 1a931d874..5aa543a77 100644
--- a/test/testtokenize.cpp
+++ b/test/testtokenize.cpp
@@ -402,6 +402,8 @@ private:
         // a = b = 0;
         TEST_CASE(multipleAssignment);
 
+        TEST_CASE(setVarId) // #6660 - crash
+
         TEST_CASE(platformWin);
         TEST_CASE(platformWin32);
         TEST_CASE(platformWin32A);
@@ -8711,6 +8713,19 @@ private:
         ASSERT_EQUALS("sizeof ( a [ 2 ] . b ) + 3 ;", tokenizeAndStringify("sizeof a[2].b+3;"));
         ASSERT_EQUALS("f ( 0 , sizeof ( ptr . bar ) ) ;", tokenizeAndStringify("f(0, sizeof ptr->bar );"));
     }
+
+    void setVarId() {
+        const char * code = "CS_PLUGIN_NAMESPACE_BEGIN(csparser)\n"
+                            "{\n"
+                            "    struct foo\n"
+                            "    {\n"
+                            "      union\n"
+                            "      {};\n"
+                            "    } halo;\n"
+                            "}\n"
+                            "CS_PLUGIN_NAMESPACE_END(csparser)\n";
+        tokenizeAndStringify(code, true);
+    }
 };
 
 REGISTER_TEST(TestTokenizer)