diff --git a/tests/test_paramdict.cpp b/tests/test_paramdict.cpp
index 219f07bb3b5..a09f4a48286 100644
--- a/tests/test_paramdict.cpp
+++ b/tests/test_paramdict.cpp
@@ -497,6 +497,147 @@ static int test_paramdict_5()
     return 0;
 }
 
+static int compare_paramdict(const ncnn::ParamDict& pd, const ncnn::ParamDict& pd0)
+{
+    for (int id = 0; ; id++)
+    {
+        const int type0 = pd0.type(id);
+        if (type0 == 0)
+        {
+            break;
+        }
+        else if (type0 == 2)
+        {
+            const int i0 = pd0.get(id, 0);
+            int i = pd.get(id, 0);
+            if (i != i0)
+            {
+                fprintf(stderr, "compare_paramdict int failed %d != %d\n", i, i0);
+                return -1;
+            }
+        }
+        else if (type0 == 3)
+        {
+            const float f0 = pd0.get(id, 0.f);
+            int f = pd.get(id, 0.f);
+            if (f != f0)
+            {
+                fprintf(stderr, "compare_paramdict float failed %f != %f\n", f, f0);
+                return -1;
+            }
+        }
+        else if (type0 == 5)
+        {
+            const ncnn::Mat ai0 = pd0.get(id, ncnn::Mat());
+            ncnn::Mat ai = pd.get(id, ncnn::Mat());
+            if (ai.w != ai0.w)
+            {
+                fprintf(stderr, "compare_paramdict int array size failed %d != %d\n", ai.w, ai0.w);
+                return -1;
+            }
+            for (int q = 0; q < ai0.w; q++)
+            {
+                int i0 = ((const int*)ai0)[q];
+                int i = ((const int*)ai)[q];
+                if (i != i0)
+                {
+                    fprintf(stderr, "compare_paramdict int array element %d failed %d != %d\n", q, i, i0);
+                    return -1;
+                }
+            }
+        }
+        else if (type0 == 6)
+        {
+            const ncnn::Mat af0 = pd0.get(id, ncnn::Mat());
+            ncnn::Mat af = pd.get(id, ncnn::Mat());
+            if (af.w != af0.w)
+            {
+                fprintf(stderr, "compare_paramdict float array size failed %d != %d\n", af.w, af0.w);
+                return -1;
+            }
+            for (int q = 0; q < af0.w; q++)
+            {
+                float f0 = af0[q];
+                float f = af[q];
+                if (f != f0)
+                {
+                    fprintf(stderr, "compare_paramdict float array element %d failed %f != %f\n", q, f, f0);
+                    return -1;
+                }
+            }
+        }
+        else if (type0 == 7)
+        {
+            const std::string s0 = pd0.get(id, "");
+            std::string s = pd.get(id, "");
+            if (s != s0)
+            {
+                fprintf(stderr, "compare_paramdict string failed %s != %s\n", s.c_str(), s0.c_str());
+                return -1;
+            }
+        }
+        else
+        {
+            fprintf(stderr, "unexpected paramdict type %d\n", type0);
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
+static int test_paramdict_6()
+{
+    const int i0 = 11;
+    const float f0 = -2.2f;
+    const std::string s0 = "qwqwqwq";
+    ncnn::Mat ai0(1);
+    {
+        int* p = ai0;
+        p[0] = 233;
+    }
+
+    ncnn::Mat af0(4);
+    {
+        float* p = af0;
+        p[0] = 2.33f;
+        p[1] = -0.2f;
+        p[2] = 0.f;
+        p[3] = 9494.f;
+    }
+
+    ncnn::ParamDict pd0;
+    pd0.set(1, i0);
+    pd0.set(2, ai0);
+    pd0.set(3, f0);
+    pd0.set(4, af0);
+    pd0.set(5, s0);
+
+    // copy
+    {
+        ncnn::ParamDict pd(pd0);
+
+        int ret = compare_paramdict(pd, pd0);
+        if (ret != 0)
+        {
+            fprintf(stderr, "paramdict copy failed\n");
+            return -1;
+        }
+    }
+
+    // assign
+    {
+        ncnn::ParamDict pd = pd0;
+
+        int ret = compare_paramdict(pd, pd0);
+        if (ret != 0)
+        {
+            fprintf(stderr, "paramdict assign failed\n");
+            return -1;
+        }
+    }
+}
+
 int main()
 {
     return 0
@@ -505,5 +646,6 @@ int main()
            || test_paramdict_2()
            || test_paramdict_3()
            || test_paramdict_4()
-           || test_paramdict_5();
+           || test_paramdict_5()
+           || test_paramdict_6();
 }