diff --git a/lib/checkclass.cpp b/lib/checkclass.cpp
index 6b4eb7da9..b699a42c6 100644
--- a/lib/checkclass.cpp
+++ b/lib/checkclass.cpp
@@ -697,7 +697,7 @@ void CheckClass::assignAllVarsVisibleFromScope(std::vector<Usage>& usageList, co
     for (const Type::BaseInfo& i : scope->definedType->derivedFrom) {
         const Type *derivedFrom = i.type;
 
-        if (derivedFrom)
+        if (derivedFrom && derivedFrom->classScope)
             assignAllVarsVisibleFromScope(usageList, derivedFrom->classScope);
     }
 }
diff --git a/test/testconstructors.cpp b/test/testconstructors.cpp
index e49a66ce2..6f5ef7f20 100644
--- a/test/testconstructors.cpp
+++ b/test/testconstructors.cpp
@@ -1440,7 +1440,7 @@ private:
                       "[test.cpp:9]: (warning) Member variable 'B::ca' is not assigned a value in 'B::operator='.\n",
                       errout.str());
 
-        check("class C : B {\n"
+        check("class C : B {\n" // don't crash
               "    virtual C& operator=(C& c);\n"
               "};\n"
               "class D : public C {\n"
@@ -1448,6 +1448,16 @@ private:
               "};\n");
         ASSERT_EQUALS("", errout.str());
 
+        check("struct B;\n" // don't crash
+              "struct D : B { D& operator=(const D&); };\n"
+              "struct E : D { E& operator=(const E& rhs); };\n"
+              "E& E::operator=(const E& rhs) {\n"
+              "    if (this != &rhs)\n"
+              "        D::operator=(rhs);\n"
+              "    return *this;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+
     }
 
     void initvar_derived_pod_struct_with_union() {