diff --git a/src/guest/bios/bios.c b/src/guest/bios/bios.c
index ab8fce76..b06117b9 100644
--- a/src/guest/bios/bios.c
+++ b/src/guest/bios/bios.c
@@ -207,7 +207,7 @@ static void bios_validate_flash(struct bios *bios) {
   }
 }
 
-static int bios_boot(struct bios *bios) {
+static void bios_boot(struct bios *bios) {
   struct dreamcast *dc = bios->dc;
   struct flash *flash = dc->flash;
   struct gdrom *gd = dc->gdrom;
@@ -221,8 +221,8 @@ static int bios_boot(struct bios *bios) {
   LOG_INFO("bios_boot using hle bootstrap");
 
   if (!gdrom_has_disc(gd)) {
-    LOG_WARNING("bios_boot failed, no disc is loaded");
-    return 0;
+    LOG_FATAL("bios_boot failed, no disc is loaded");
+    return;
   }
 
   /* load IP.BIN bootstrap */
@@ -235,8 +235,8 @@ static int bios_boot(struct bios *bios) {
     int read = gdrom_read_sectors(gd, data_session.fad, 16, GD_SECTOR_ANY,
                                   GD_MASK_DATA, tmp, sizeof(tmp));
     if (!read) {
-      LOG_WARNING("bios_boot failed to copy IP.BIN");
-      return 0;
+      LOG_FATAL("bios_boot failed to copy IP.BIN");
+      return;
     }
 
     sh4_memcpy_to_guest(dc->mem, BOOT1_ADDR, tmp, read);
@@ -251,9 +251,9 @@ static int bios_boot(struct bios *bios) {
     uint8_t *tmp = malloc(len);
     int read = gdrom_read_bytes(gd, fad, len, tmp, len);
     if (read != len) {
-      LOG_WARNING("bios_boot failed to copy bootfile");
+      LOG_FATAL("bios_boot failed to copy bootfile");
       free(tmp);
-      return 0;
+      return;
     }
 
     sh4_memcpy_to_guest(dc->mem, BOOT2_ADDR, tmp, read);
@@ -291,8 +291,6 @@ static int bios_boot(struct bios *bios) {
 
   /* start executing at license screen code inside of ip.bin */
   ctx->pc = 0xac008300;
-
-  return 1;
 }
 
 static int bios_post_init(struct device *dev) {
@@ -331,7 +329,8 @@ int bios_invalid_instr(struct bios *bios) {
   /* if an actual boot rom wasn't loaded into memory, a valid instruction won't
      exist at 0x0, causing an immediate trap on start */
   if (pc == 0x0) {
-    return bios_boot(bios);
+    bios_boot(bios);
+    return 1;
   }
 
   int handled = 1;
diff --git a/src/guest/memory.c b/src/guest/memory.c
index 1512bb93..87e34158 100644
--- a/src/guest/memory.c
+++ b/src/guest/memory.c
@@ -173,8 +173,6 @@ enum {
 #define define_memcpy(space)                                                   \
   void space##_memcpy(struct memory *mem, uint32_t dst, uint32_t src,          \
                       int size) {                                              \
-    CHECK(size % 4 == 0);                                                      \
-                                                                               \
     uint8_t *pdst = NULL;                                                      \
     mmio_write_cb write = NULL;                                                \
     mmio_write_string_cb write_string = NULL;                                  \
@@ -195,10 +193,10 @@ enum {
     } else {                                                                   \
       uint32_t end = src + size;                                               \
       while (src < end) {                                                      \
-        uint32_t data = read(mem->dc->space, src, 0xffffffff);                 \
-        write(mem->dc->space, dst, data, 0xffffffff);                          \
-        src += 4;                                                              \
-        dst += 4;                                                              \
+        uint8_t data = read(mem->dc->space, src, 0xff);                        \
+        write(mem->dc->space, dst, data, 0xff);                                \
+        src++;                                                                 \
+        dst++;                                                                 \
       }                                                                        \
     }                                                                          \
   }
@@ -206,8 +204,6 @@ enum {
 #define define_memcpy_to_host(space)                                           \
   void space##_memcpy_to_host(struct memory *mem, void *ptr, uint32_t src,     \
                               int size) {                                      \
-    CHECK(size % 4 == 0);                                                      \
-                                                                               \
     uint8_t *pdst = ptr;                                                       \
     uint8_t *psrc = NULL;                                                      \
     mmio_read_cb read = NULL;                                                  \
@@ -221,37 +217,35 @@ enum {
     } else {                                                                   \
       uint32_t end = src + size;                                               \
       while (src < end) {                                                      \
-        *(uint32_t *)pdst = read(mem->dc->space, src, 0xffffffff);             \
-        pdst += 4;                                                             \
-        src += 4;                                                              \
+        *pdst = read(mem->dc->space, src, 0xff);                               \
+        pdst++;                                                                \
+        src++;                                                                 \
       }                                                                        \
     }                                                                          \
   }
 
-#define define_memcpy_to_guest(space)                              \
-  void space##_memcpy_to_guest(struct memory *mem, uint32_t dst,   \
-                               const void *ptr, int size) {        \
-    CHECK(size % 4 == 0);                                          \
-                                                                   \
-    const uint8_t *psrc = ptr;                                     \
-    uint8_t *pdst = NULL;                                          \
-    mmio_write_cb write = NULL;                                    \
-    mmio_write_string_cb write_string = NULL;                      \
-    space##_lookup_ex(mem, dst, NULL, &pdst, NULL, &write, NULL,   \
-                      &write_string);                              \
-                                                                   \
-    if (pdst) {                                                    \
-      memcpy(pdst, psrc, size);                                    \
-    } else if (write_string) {                                     \
-      write_string(mem->dc->space, dst, psrc, size);               \
-    } else {                                                       \
-      uint32_t end = dst + size;                                   \
-      while (dst < end) {                                          \
-        write(mem->dc->space, dst, *(uint32_t *)psrc, 0xffffffff); \
-        psrc += 4;                                                 \
-        dst += 4;                                                  \
-      }                                                            \
-    }                                                              \
+#define define_memcpy_to_guest(space)                            \
+  void space##_memcpy_to_guest(struct memory *mem, uint32_t dst, \
+                               const void *ptr, int size) {      \
+    const uint8_t *psrc = ptr;                                   \
+    uint8_t *pdst = NULL;                                        \
+    mmio_write_cb write = NULL;                                  \
+    mmio_write_string_cb write_string = NULL;                    \
+    space##_lookup_ex(mem, dst, NULL, &pdst, NULL, &write, NULL, \
+                      &write_string);                            \
+                                                                 \
+    if (pdst) {                                                  \
+      memcpy(pdst, psrc, size);                                  \
+    } else if (write_string) {                                   \
+      write_string(mem->dc->space, dst, psrc, size);             \
+    } else {                                                     \
+      uint32_t end = dst + size;                                 \
+      while (dst < end) {                                        \
+        write(mem->dc->space, dst, *psrc, 0xff);                 \
+        psrc++;                                                  \
+        dst++;                                                   \
+      }                                                          \
+    }                                                            \
   }
 
 #define define_write_bytes(space, name, data_type)                           \