diff --git a/src/devices/bus/isa/3c503.cpp b/src/devices/bus/isa/3c503.cpp
index 041b403cabb..6c5e812177b 100644
--- a/src/devices/bus/isa/3c503.cpp
+++ b/src/devices/bus/isa/3c503.cpp
@@ -3,6 +3,8 @@
 #include "emu.h"
 #include "3c503.h"
 
+#include "multibyte.h"
+
 #define SADDR 0xcc000
 
 void el2_3c503_device::device_add_mconfig(machine_config &config)
@@ -24,10 +26,13 @@ el2_3c503_device::el2_3c503_device(const machine_config& mconfig, const char* ta
 }
 
 void el2_3c503_device::device_start() {
-	char mac[7];
+	uint8_t mac[6];
 	uint32_t num = machine().rand();
 	memset(m_prom, 0x57, 16);
-	snprintf(mac, std::size(mac), "\x02\x60\x8c%c%c%c", (num >> 16) & 0xff, (num >> 8) & 0xff, num & 0xff);
+	mac[0] = 0x02;
+	mac[1] = 0x60;
+	mac[2] = 0x8c;
+	put_u24be(mac+3, num);
 	memcpy(m_prom, mac, 6);
 	memset(m_rom, 0, 8*1024); // empty
 	m_dp8390->set_mac(mac);
diff --git a/src/devices/bus/isa/ne1000.cpp b/src/devices/bus/isa/ne1000.cpp
index a290b076628..62c7187e377 100644
--- a/src/devices/bus/isa/ne1000.cpp
+++ b/src/devices/bus/isa/ne1000.cpp
@@ -3,6 +3,8 @@
 #include "emu.h"
 #include "ne1000.h"
 
+#include "multibyte.h"
+
 
 DEFINE_DEVICE_TYPE(NE1000, ne1000_device, "ne1000", "NE1000 Network Adapter")
 
@@ -23,10 +25,11 @@ ne1000_device::ne1000_device(const machine_config &mconfig, const char *tag, dev
 }
 
 void ne1000_device::device_start() {
-	char mac[7];
+	uint8_t mac[6];
 	uint32_t num = machine().rand();
 	memset(m_prom, 0x57, 16);
-	sprintf(mac+2, "\x1b%c%c%c", (num >> 16) & 0xff, (num >> 8) & 0xff, num & 0xff);
+	mac[2] = 0x1b;
+	put_u24be(mac+3, num);
 	mac[0] = 0; mac[1] = 0;  // avoid gcc warning
 	memcpy(m_prom, mac, 6);
 	m_dp8390->set_mac(mac);
diff --git a/src/devices/bus/isa/ne2000.cpp b/src/devices/bus/isa/ne2000.cpp
index efd448fe3da..452aceb55c5 100644
--- a/src/devices/bus/isa/ne2000.cpp
+++ b/src/devices/bus/isa/ne2000.cpp
@@ -3,6 +3,8 @@
 #include "emu.h"
 #include "ne2000.h"
 
+#include "multibyte.h"
+
 
 DEFINE_DEVICE_TYPE(NE2000, ne2000_device, "ne2000", "NE2000 Network Adapter")
 
@@ -23,10 +25,11 @@ ne2000_device::ne2000_device(const machine_config& mconfig, const char* tag, dev
 }
 
 void ne2000_device::device_start() {
-	char mac[7];
+	uint8_t mac[6];
 	uint32_t num = machine().rand();
 	memset(m_prom, 0x57, 16);
-	sprintf(mac+2, "\x1b%c%c%c", (num >> 16) & 0xff, (num >> 8) & 0xff, num & 0xff);
+	mac[2] = 0x1b;
+	put_u24be(mac+3, num);
 	mac[0] = 0; mac[1] = 0;  // avoid gcc warning
 	memcpy(m_prom, mac, 6);
 	m_dp8390->set_mac(mac);
diff --git a/src/devices/bus/nubus/nubus_asntmc3b.cpp b/src/devices/bus/nubus/nubus_asntmc3b.cpp
index c7a846fe7b2..70c56dc40f7 100644
--- a/src/devices/bus/nubus/nubus_asntmc3b.cpp
+++ b/src/devices/bus/nubus/nubus_asntmc3b.cpp
@@ -15,6 +15,8 @@
 #include "emu.h"
 #include "nubus_asntmc3b.h"
 
+#include "multibyte.h"
+
 #define MAC8390_ROM_REGION  "asntm3b_rom"
 #define MAC8390_839X  "dp83902"
 
@@ -95,10 +97,11 @@ nubus_appleenet_device::nubus_appleenet_device(const machine_config &mconfig, co
 void nubus_mac8390_device::device_start()
 {
 	uint32_t slotspace;
-	char mac[7];
+	uint8_t mac[6];
 	uint32_t num = machine().rand();
 	memset(m_prom, 0x57, 16);
-	sprintf(mac+2, "\x1b%c%c%c", (num >> 16) & 0xff, (num >> 8) & 0xff, num & 0xff);
+	mac[2] = 0x1b;
+	put_u24be(mac+3, num);
 	mac[0] = mac[1] = 0;  // avoid gcc warning
 	memcpy(m_prom, mac, 6);
 	m_dp83902->set_mac(mac);
diff --git a/src/devices/bus/x68k/x68k_neptunex.cpp b/src/devices/bus/x68k/x68k_neptunex.cpp
index 56ffe39951f..ab03f73741c 100644
--- a/src/devices/bus/x68k/x68k_neptunex.cpp
+++ b/src/devices/bus/x68k/x68k_neptunex.cpp
@@ -9,6 +9,8 @@
 
 #include "machine/dp8390.h"
 
+#include "multibyte.h"
+
 
 //**************************************************************************
 //  DEVICE DEFINITIONS
@@ -39,11 +41,12 @@ x68k_neptune_device::x68k_neptune_device(const machine_config &mconfig, const ch
 
 void x68k_neptune_device::device_start()
 {
-	char mac[7];
+	uint8_t mac[6];
 	uint32_t num = machine().rand();
 	m_slot = dynamic_cast<x68k_expansion_slot_device *>(owner());
 	memset(m_prom, 0x57, 16);
-	sprintf(mac+2, "\x1b%c%c%c", (num >> 16) & 0xff, (num >> 8) & 0xff, num & 0xff);
+	mac[2] = 0x1b;
+	put_u24be(mac+3, num);
 	mac[0] = 0; mac[1] = 0;  // avoid gcc warning
 	memcpy(m_prom, mac, 6);
 	m_dp8390->set_mac(mac);
diff --git a/src/devices/machine/am79c90.cpp b/src/devices/machine/am79c90.cpp
index a48d2ad841c..8c6a36221f3 100644
--- a/src/devices/machine/am79c90.cpp
+++ b/src/devices/machine/am79c90.cpp
@@ -694,7 +694,7 @@ void am7990_device_base::initialize()
 	put_u16le(&m_physical_addr[0], init_block[1]);
 	put_u16le(&m_physical_addr[2], init_block[2]);
 	put_u16le(&m_physical_addr[4], init_block[3]);
-	set_mac((char *)m_physical_addr);
+	set_mac(m_physical_addr);
 
 	m_logical_addr_filter = (u64(init_block[7]) << 48) | (u64(init_block[6]) << 32) | (u32(init_block[5]) << 16) | init_block[4];
 
diff --git a/src/devices/machine/cs8900a.cpp b/src/devices/machine/cs8900a.cpp
index 92df2892ddc..b91957c29b2 100644
--- a/src/devices/machine/cs8900a.cpp
+++ b/src/devices/machine/cs8900a.cpp
@@ -923,7 +923,7 @@ void cs8900a_device::cs8900_sideeffects_write_pp(u16 ppaddress, int odd_address)
 
 		/* the MAC address has been changed */
 		cs8900_ia_mac[ppaddress - CS8900_PP_ADDR_MAC_ADDR + odd_address] = GET_PP_8(ppaddress + odd_address);
-		set_mac((char *)cs8900_ia_mac);
+		set_mac(cs8900_ia_mac);
 
 		if (odd_address && (ppaddress == CS8900_PP_ADDR_MAC_ADDR + 4))
 			LOGMASKED(CS8900_DEBUG, "set MAC address: %02x:%02x:%02x:%02x:%02x:%02x",
diff --git a/src/devices/machine/dp8390.cpp b/src/devices/machine/dp8390.cpp
index 493c21f0ca7..2ed12551e78 100644
--- a/src/devices/machine/dp8390.cpp
+++ b/src/devices/machine/dp8390.cpp
@@ -422,7 +422,7 @@ void dp8390_device::cs_write(offs_t offset, uint8_t data) {
 	case 0x45:
 	case 0x46:
 		m_regs.par[(offset & 0x7)-1] = data;
-		set_mac((const char *)m_regs.par);
+		set_mac(m_regs.par);
 		break;
 	case 0x47:
 		m_regs.curr = data;
diff --git a/src/devices/machine/i82586.cpp b/src/devices/machine/i82586.cpp
index c017a3501d4..d92a0817e91 100644
--- a/src/devices/machine/i82586.cpp
+++ b/src/devices/machine/i82586.cpp
@@ -838,7 +838,7 @@ bool i82586_device::cu_iasetup()
 	put_u32le(&mac[2], data);
 
 	LOG("cu_iasetup individual address %02x:%02x:%02x:%02x:%02x:%02x\n", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
-	set_mac((char *)mac);
+	set_mac(mac);
 
 	return true;
 }
@@ -1367,7 +1367,7 @@ bool i82596_device::cu_iasetup()
 	}
 
 	LOG("cu_iasetup individual address %02x:%02x:%02x:%02x:%02x:%02x\n", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
-	set_mac((char *)mac);
+	set_mac(mac);
 
 	return true;
 }
diff --git a/src/devices/machine/mb8795.cpp b/src/devices/machine/mb8795.cpp
index 53e29c00e63..7d619a18d90 100644
--- a/src/devices/machine/mb8795.cpp
+++ b/src/devices/machine/mb8795.cpp
@@ -180,7 +180,7 @@ void mb8795_device::mac_w(offs_t offset, uint8_t data)
 {
 	if(offset < 6) {
 		mac[offset] = data;
-		set_mac((const char *)mac);
+		set_mac(mac);
 	}
 }
 
diff --git a/src/devices/machine/smc91c9x.cpp b/src/devices/machine/smc91c9x.cpp
index 9c381ba64f9..a27c1f7d281 100644
--- a/src/devices/machine/smc91c9x.cpp
+++ b/src/devices/machine/smc91c9x.cpp
@@ -10,6 +10,8 @@
 
 #include "emu.h"
 #include "smc91c9x.h"
+
+#include "multibyte.h"
 #include <sstream>
 #include <iomanip>
 
@@ -972,7 +974,12 @@ void smc91c9x_device::write(offs_t offset, u16 data, u16 mem_mask)
 			if ( ACCESSING_BITS_8_15 )
 			{
 				set_promisc(m_reg[B0_RCR] & PRMS);
-				set_mac((char *)&m_reg[B1_IA0_1]);
+
+				u8 mac[6];
+				put_u16le(&mac[0], m_reg[B1_IA0_1]);
+				put_u16le(&mac[2], m_reg[B1_IA2_3]);
+				put_u16le(&mac[4], m_reg[B1_IA4_5]);
+				set_mac(mac);
 			}
 			break;
 
diff --git a/src/emu/dinetwork.cpp b/src/emu/dinetwork.cpp
index 2091ac6a2c3..7333fd25de8 100644
--- a/src/emu/dinetwork.cpp
+++ b/src/emu/dinetwork.cpp
@@ -12,7 +12,7 @@ device_network_interface::device_network_interface(const machine_config &mconfig
 	// Convert to Mibps to Bps
 	m_bandwidth = bandwidth << (20 - 3);
 	m_mtu = mtu;
-	set_mac("\0\0\0\0\0\0");
+	memset(m_mac, 0, 6);
 	m_intf = -1;
 	m_loopback_control = false;
 }
@@ -107,7 +107,7 @@ void device_network_interface::set_promisc(bool promisc)
 	if(m_dev) m_dev->set_promisc(promisc);
 }
 
-void device_network_interface::set_mac(const char *mac)
+void device_network_interface::set_mac(const u8 *mac)
 {
 	memcpy(m_mac, mac, 6);
 	if(m_dev) m_dev->set_mac(m_mac);
diff --git a/src/emu/dinetwork.h b/src/emu/dinetwork.h
index c2629f665fc..6dd062c16aa 100644
--- a/src/emu/dinetwork.h
+++ b/src/emu/dinetwork.h
@@ -16,7 +16,7 @@ public:
 
 	void set_interface(int id);
 	void set_promisc(bool promisc);
-	void set_mac(const char *mac);
+	void set_mac(const u8 *mac);
 	void set_loopback(bool loopback);
 
 	const char *get_mac() const { return m_mac; }
diff --git a/src/emu/network.cpp b/src/emu/network.cpp
index 0ffff1616cc..4566298a994 100644
--- a/src/emu/network.cpp
+++ b/src/emu/network.cpp
@@ -57,7 +57,7 @@ void network_manager::config_load(config_type cfg_type, config_level cfg_level,
 						network.set_interface(interface);
 						const char *mac_addr = node->get_attribute_string("mac", nullptr);
 						if (mac_addr != nullptr && strlen(mac_addr) == 17) {
-							char mac[7];
+							uint8_t mac[6];
 							unsigned int mac_num[6];
 							sscanf(mac_addr, "%02x:%02x:%02x:%02x:%02x:%02x", &mac_num[0], &mac_num[1], &mac_num[2], &mac_num[3], &mac_num[4], &mac_num[5]);
 							for (int i = 0; i<6; i++) mac[i] = mac_num[i];