diff --git a/unittest/formats/test_dump_atom.cpp b/unittest/formats/test_dump_atom.cpp
index 0140b1a9e4..3eea4c2746 100644
--- a/unittest/formats/test_dump_atom.cpp
+++ b/unittest/formats/test_dump_atom.cpp
@@ -699,6 +699,66 @@ TEST_F(DumpAtomTest, binary_write_dump)
     delete_file(dump_file);
 }
 
+TEST_F(DumpAtomTest, frequency)
+{
+    auto dump_file = dump_filename("frequency");
+    BEGIN_HIDE_OUTPUT();
+    command("dump id all atom 5 " + dump_file);
+    command("run 15 post no");
+    command("run 12 post no");
+    END_HIDE_OUTPUT();
+
+    // NOTE: must reset to current timestep (27) to avoid unexpected issues with following
+    TEST_FAILURE(".*ERROR: Cannot reset timestep with active dump - must undump first.*",
+                 command("reset_timestep 27"););
+
+    BEGIN_HIDE_OUTPUT();
+    command("run 3 post no");
+    command("undump id");
+    command("reset_timestep 5");
+    command("dump id all atom 10 " + dump_file);
+    command("dump_modify id append yes");
+    command("run 20 post no");
+    command("undump id");
+    END_HIDE_OUTPUT();
+
+    std::vector<std::string> expected, values;
+    values   = extract_items(dump_file, "TIMESTEP");
+    expected = {"0", "5", "10", "15", "20", "25", "30", "10", "20"};
+    ASSERT_EQ(values.size(), expected.size());
+    for (int i = 0; i < expected.size(); ++i)
+        ASSERT_THAT(values[i], Eq(expected[i]));
+
+    BEGIN_HIDE_OUTPUT();
+    command("reset_timestep 10");
+    command("dump id all atom 10 " + dump_file);
+    command("run 20 post no");
+    command("undump id");
+    END_HIDE_OUTPUT();
+
+    values   = extract_items(dump_file, "TIMESTEP");
+    expected = {"10", "20", "30"};
+    ASSERT_EQ(values.size(), expected.size());
+    for (int i = 0; i < expected.size(); ++i)
+        ASSERT_THAT(values[i], Eq(expected[i]));
+
+    BEGIN_HIDE_OUTPUT();
+    command("reset_timestep 0");
+    command("dump id all atom 10 " + dump_file);
+    command("minimize 0.0 0.0 15 30");
+    command("run 20 post no");
+    command("undump id");
+    END_HIDE_OUTPUT();
+
+    values   = extract_items(dump_file, "TIMESTEP");
+    expected = {"0", "10", "15", "20", "30"};
+    ASSERT_EQ(values.size(), expected.size());
+    for (int i = 0; i < expected.size(); ++i)
+        ASSERT_THAT(values[i], Eq(expected[i]));
+
+    delete_file(dump_file);
+}
+
 //-------------------------------------------------------------------------------------------------
 // dump_modify
 //-------------------------------------------------------------------------------------------------