diff --git a/beacon-chain/sync/backfill/service_test.go b/beacon-chain/sync/backfill/service_test.go
index 977f16cc2dfa..bb9d1a28e5f4 100644
--- a/beacon-chain/sync/backfill/service_test.go
+++ b/beacon-chain/sync/backfill/service_test.go
@@ -107,3 +107,28 @@ func testReadN(t *testing.T, ctx context.Context, c chan batch, n int, into []ba
 	}
 	return into
 }
+
+func TestBackfillMinSlotDefault(t *testing.T) {
+	oe := helpers.MinEpochsForBlockRequests()
+	current := primitives.Slot((oe + 100).Mul(uint64(params.BeaconConfig().SlotsPerEpoch)))
+	s := &Service{}
+	specMin := minimumBackfillSlot(current)
+
+	t.Run("equal to specMin", func(t *testing.T) {
+		opt := WithMinimumSlot(specMin)
+		require.NoError(t, opt(s))
+		require.Equal(t, specMin, s.ms(current))
+	})
+	t.Run("older than specMin", func(t *testing.T) {
+		opt := WithMinimumSlot(specMin - 1)
+		require.NoError(t, opt(s))
+		// if WithMinimumSlot is older than the spec minimum, we should use it.
+		require.Equal(t, specMin-1, s.ms(current))
+	})
+	t.Run("newer than specMin", func(t *testing.T) {
+		opt := WithMinimumSlot(specMin + 1)
+		require.NoError(t, opt(s))
+		// if WithMinimumSlot is newer than the spec minimum, we should use the spec minimum
+		require.Equal(t, specMin, s.ms(current))
+	})
+}