diff --git a/src/mess/drivers/c64.c b/src/mess/drivers/c64.c
index 691a0b54f93..83d5dd9f9ca 100644
--- a/src/mess/drivers/c64.c
+++ b/src/mess/drivers/c64.c
@@ -1088,6 +1088,7 @@ static MACHINE_CONFIG_START( ntsc, c64_state )
 	// basic hardware
 	MCFG_CPU_ADD(M6510_TAG, M6510, XTAL_14_31818MHz/14)
 	MCFG_CPU_PROGRAM_MAP(c64_mem)
+	MCFG_M6502_DISABLE_DIRECT() // address decoding is 100% dynamic, no RAM/ROM banks
 	MCFG_M6510_PORT_CALLBACKS(READ8(c64_state, cpu_r), WRITE8(c64_state, cpu_w))
 	MCFG_M6510_PORT_PULLS(0x17, 0xc8)
 	MCFG_QUANTUM_PERFECT_CPU(M6510_TAG)
@@ -1243,6 +1244,7 @@ static MACHINE_CONFIG_START( pal, c64_state )
 	// basic hardware
 	MCFG_CPU_ADD(M6510_TAG, M6510, XTAL_17_734472MHz/18)
 	MCFG_CPU_PROGRAM_MAP(c64_mem)
+	MCFG_M6502_DISABLE_DIRECT() // address decoding is 100% dynamic, no RAM/ROM banks
 	MCFG_M6510_PORT_CALLBACKS(READ8(c64_state, cpu_r), WRITE8(c64_state, cpu_w))
 	MCFG_M6510_PORT_PULLS(0x17, 0xc8)
 	MCFG_QUANTUM_PERFECT_CPU(M6510_TAG)
@@ -1376,6 +1378,7 @@ static MACHINE_CONFIG_START( pal_gs, c64gs_state )
 	// basic hardware
 	MCFG_CPU_ADD(M6510_TAG, M6510, XTAL_17_734472MHz/18)
 	MCFG_CPU_PROGRAM_MAP(c64_mem)
+	MCFG_M6502_DISABLE_DIRECT() // address decoding is 100% dynamic, no RAM/ROM banks
 	MCFG_M6510_PORT_CALLBACKS(READ8(c64gs_state, cpu_r), WRITE8(c64gs_state, cpu_w))
 	MCFG_M6510_PORT_PULLS(0x07, 0xc0)
 	MCFG_QUANTUM_PERFECT_CPU(M6510_TAG)