diff --git a/hw/firmware_abi.h b/hw/firmware_abi.h
index 4999493637885b842e002bf1d4aeb834b11928be..713484d41465af7494a9dd2a873ae63f4ed705c2 100644
--- a/hw/firmware_abi.h
+++ b/hw/firmware_abi.h
@@ -139,7 +139,7 @@ OpenBIOS_finish_partition(struct OpenBIOS_nvpart_v1 *header, uint32_t size)
 }
 
 static inline uint32_t
-OpenBIOS_set_var(uint8_t *nvram, uint32_t addr, const unsigned char *str)
+OpenBIOS_set_var(uint8_t *nvram, uint32_t addr, const char *str)
 {
     uint32_t len;
 
diff --git a/hw/sun4m.c b/hw/sun4m.c
index 4bfc333a191f85418d7cb3040624e8c046e9d69f..e1ff225e381488581721bd43c0fa603b398c606e 100644
--- a/hw/sun4m.c
+++ b/hw/sun4m.c
@@ -159,7 +159,7 @@ static int nvram_boot_set(void *opaque, const char *boot_device)
     for (i = 0; i < sizeof(image); i++)
         image[i] = m48t59_read(nvram, i) & 0xff;
 
-    strcpy(header->boot_devices, boot_device);
+    strcpy((char *)header->boot_devices, boot_device);
     header->nboot_devices = strlen(boot_device) & 0xff;
     header->crc = cpu_to_be16(OHW_compute_crc(header, 0x00, 0xF8));
 
@@ -187,17 +187,17 @@ static void nvram_init(m48t59_t *nvram, uint8_t *macaddr, const char *cmdline,
     memset(image, '\0', sizeof(image));
 
     // Try to match PPC NVRAM
-    strcpy(header->struct_ident, "QEMU_BIOS");
+    strcpy((char *)header->struct_ident, "QEMU_BIOS");
     header->struct_version = cpu_to_be32(3); /* structure v3 */
 
     header->nvram_size = cpu_to_be16(0x2000);
     header->nvram_arch_ptr = cpu_to_be16(sizeof(ohwcfg_v3_t));
     header->nvram_arch_size = cpu_to_be16(sizeof(struct sparc_arch_cfg));
-    strcpy(header->arch, arch);
+    strcpy((char *)header->arch, arch);
     header->nb_cpus = smp_cpus & 0xff;
     header->RAM0_base = 0;
     header->RAM0_size = cpu_to_be64((uint64_t)RAM_size);
-    strcpy(header->boot_devices, boot_devices);
+    strcpy((char *)header->boot_devices, boot_devices);
     header->nboot_devices = strlen(boot_devices) & 0xff;
     header->kernel_image = cpu_to_be64((uint64_t)KERNEL_LOAD_ADDR);
     header->kernel_size = cpu_to_be64((uint64_t)kernel_size);
diff --git a/hw/sun4u.c b/hw/sun4u.c
index 49f049452dd77c960ba410deb85da6b110bb4581..f97c7a05b92824d6db956663295d8ca4eae65f46 100644
--- a/hw/sun4u.c
+++ b/hw/sun4u.c
@@ -78,7 +78,7 @@ static int nvram_boot_set(void *opaque, const char *boot_device)
     for (i = 0; i < sizeof(image); i++)
         image[i] = m48t59_read(nvram, i) & 0xff;
 
-    strcpy(header->boot_devices, boot_device);
+    strcpy((char *)header->boot_devices, boot_device);
     header->nboot_devices = strlen(boot_device) & 0xff;
     header->crc = cpu_to_be16(OHW_compute_crc(header, 0x00, 0xF8));
 
@@ -91,7 +91,7 @@ static int nvram_boot_set(void *opaque, const char *boot_device)
 extern int nographic;
 
 static int sun4u_NVRAM_set_params (m48t59_t *nvram, uint16_t NVRAM_size,
-                                   const unsigned char *arch,
+                                   const char *arch,
                                    ram_addr_t RAM_size,
                                    const char *boot_devices,
                                    uint32_t kernel_image, uint32_t kernel_size,
@@ -110,17 +110,17 @@ static int sun4u_NVRAM_set_params (m48t59_t *nvram, uint16_t NVRAM_size,
     memset(image, '\0', sizeof(image));
 
     // Try to match PPC NVRAM
-    strcpy(header->struct_ident, "QEMU_BIOS");
+    strcpy((char *)header->struct_ident, "QEMU_BIOS");
     header->struct_version = cpu_to_be32(3); /* structure v3 */
 
     header->nvram_size = cpu_to_be16(NVRAM_size);
     header->nvram_arch_ptr = cpu_to_be16(sizeof(ohwcfg_v3_t));
     header->nvram_arch_size = cpu_to_be16(sizeof(struct sparc_arch_cfg));
-    strcpy(header->arch, arch);
+    strcpy((char *)header->arch, arch);
     header->nb_cpus = smp_cpus & 0xff;
     header->RAM0_base = 0;
     header->RAM0_size = cpu_to_be64((uint64_t)RAM_size);
-    strcpy(header->boot_devices, boot_devices);
+    strcpy((char *)header->boot_devices, boot_devices);
     header->nboot_devices = strlen(boot_devices) & 0xff;
     header->kernel_image = cpu_to_be64((uint64_t)kernel_image);
     header->kernel_size = cpu_to_be64((uint64_t)kernel_size);