diff --git a/lib/checkvaarg.cpp b/lib/checkvaarg.cpp
index d02e24738..8e25fca71 100644
--- a/lib/checkvaarg.cpp
+++ b/lib/checkvaarg.cpp
@@ -104,7 +104,6 @@ void CheckVaarg::va_list_usage()
                 if (tok->linkAt(1)->previous()->varId() == var->declarationId()) { // Source
                     if (!open)
                         va_list_usedBeforeStartedError(tok, var->name());
-                    nopen = false;
                 }
                 if (tok->tokAt(2)->varId() == var->declarationId()) { // Destination
                     if (open)
diff --git a/test/testvaarg.cpp b/test/testvaarg.cpp
index 446aa0761..8e7c6f11f 100644
--- a/test/testvaarg.cpp
+++ b/test/testvaarg.cpp
@@ -167,6 +167,15 @@ private:
               "    va_end(arg_ptr);\n"
               "}");
         ASSERT_EQUALS("", errout.str());
+
+        // #6066
+        check("void Format(va_list v1) {\n"
+              "    va_list v2;\n"
+              "    va_copy(v2, v1);\n"
+              "    foo(va_arg(v1, float));\n"
+              "    va_end(v2);\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void va_start_subsequentCalls() {