diff --git a/src/mame/includes/fidelbase.h b/src/mame/includes/fidelbase.h
index a79fa923dd1..938c01cb1df 100644
--- a/src/mame/includes/fidelbase.h
+++ b/src/mame/includes/fidelbase.h
@@ -41,7 +41,7 @@ public:
 	// in case reset button is directly tied to maincpu reset pin
 	virtual DECLARE_INPUT_CHANGED_MEMBER(reset_button) { m_maincpu->set_input_line(INPUT_LINE_RESET, newval ? ASSERT_LINE : CLEAR_LINE); }
 
-	DECLARE_INPUT_CHANGED_MEMBER(div_changed);
+	DECLARE_INPUT_CHANGED_MEMBER(div_changed) { div_refresh(newval); }
 
 protected:
 	// devices/pointers
@@ -71,6 +71,7 @@ protected:
 	u8 div_trampoline_r(offs_t offset);
 	void div_set_cpu_freq(offs_t offset);
 	void div_trampoline(address_map &map);
+	void div_refresh(ioport_value val = 0xff);
 	u16 m_div_status;
 	ioport_value m_div_config;
 	emu_timer *m_div_timer;
diff --git a/src/mame/machine/fidelbase.cpp b/src/mame/machine/fidelbase.cpp
index 540761962a2..2195dae45f0 100644
--- a/src/mame/machine/fidelbase.cpp
+++ b/src/mame/machine/fidelbase.cpp
@@ -66,9 +66,7 @@ void fidelbase_state::machine_reset()
 	chessbase_state::machine_reset();
 
 	// init cpu divider (optional)
-	ioport_port *inp = ioport("div_config");
-	if (inp != nullptr)
-		div_changed(*inp->field(0x03), nullptr, 0, inp->read());
+	div_refresh();
 }
 
 
@@ -139,14 +137,24 @@ void fidelbase_state::div_trampoline(address_map &map)
 	map(0x0000, 0xffff).rw(FUNC(fidelbase_state::div_trampoline_r), FUNC(fidelbase_state::div_trampoline_w));
 }
 
-INPUT_CHANGED_MEMBER(fidelbase_state::div_changed)
+void fidelbase_state::div_refresh(ioport_value val)
 {
+	if (val == 0xff)
+	{
+		// bail out if there is no cpu divider
+		ioport_port *inp = ioport("div_config");
+		if (inp == nullptr)
+			return;
+
+		val = inp->read();
+	}
+
 	m_maincpu->set_clock_scale(1.0);
 	m_div_status = ~0;
-	m_div_config = newval;
+	m_div_config = val;
 
 	// stop high frequency background timer if cpu divider is disabled
-	attotime period = (newval) ? attotime::from_hz(m_maincpu->clock()) : attotime::never;
+	attotime period = (val) ? attotime::from_hz(m_maincpu->clock()) : attotime::never;
 	m_div_timer->adjust(period, 0, period);
 }