diff --git a/arch/sandbox/cpu/os.c b/arch/sandbox/cpu/os.c
index da96ebe..f5c9a8a 100644
--- a/arch/sandbox/cpu/os.c
+++ b/arch/sandbox/cpu/os.c
@@ -47,12 +47,24 @@
 
 ssize_t os_read(int fd, void *buf, size_t count)
 {
-	return read(fd, buf, count);
+	ssize_t ret;
+
+	ret = read(fd, buf, count);
+	if (ret == -1)
+		return -errno;
+
+	return ret;
 }
 
 ssize_t os_write(int fd, const void *buf, size_t count)
 {
-	return write(fd, buf, count);
+	ssize_t ret;
+
+	ret = write(fd, buf, count);
+	if (ret == -1)
+		return -errno;
+
+	return ret;
 }
 
 int os_printf(const char *fmt, ...)
@@ -69,6 +81,8 @@
 
 off_t os_lseek(int fd, off_t offset, int whence)
 {
+	off_t ret;
+
 	if (whence == OS_SEEK_SET)
 		whence = SEEK_SET;
 	else if (whence == OS_SEEK_CUR)
@@ -77,7 +91,11 @@
 		whence = SEEK_END;
 	else
 		os_exit(1);
-	return lseek(fd, offset, whence);
+	ret = lseek(fd, offset, whence);
+	if (ret == -1)
+		return -errno;
+
+	return ret;
 }
 
 int os_open(const char *pathname, int os_flags)
diff --git a/arch/sandbox/cpu/spl.c b/arch/sandbox/cpu/spl.c
index 49abe02..e86193d 100644
--- a/arch/sandbox/cpu/spl.c
+++ b/arch/sandbox/cpu/spl.c
@@ -195,16 +195,14 @@
 
 	ret = os_lseek(load_ctx->fd, offset, OS_SEEK_SET);
 	if (ret < 0) {
-		printf("Failed to seek to %zx, got %zx (errno=%d)\n", offset,
-		       ret, errno);
-		return log_msg_ret("lse", -errno);
+		printf("Failed to seek to %zx, got %zx\n", offset, ret);
+		return log_msg_ret("lse", ret);
 	}
 
 	res = os_read(load_ctx->fd, buf, size);
 	if (res < 0) {
-		printf("Failed to read %lx bytes, got %ld (errno=%d)\n",
-		       size, res, errno);
-		return log_msg_ret("osr", -errno);
+		printf("Failed to read %lx bytes, got %ld\n", size, res);
+		return log_msg_ret("osr", res);
 	}
 
 	return size;
@@ -238,9 +236,9 @@
 	}
 	ret = os_read(fd, header, sizeof(*header));
 	if (ret != sizeof(*header)) {
-		printf("Failed to read %lx bytes, got %ld (errno=%d)\n",
-		       sizeof(*header), ret, -errno);
-		return log_msg_ret("rea", -errno);
+		printf("Failed to read %lx bytes, got %d\n", sizeof(*header),
+		       ret);
+		return log_msg_ret("rea", ret);
 	}
 	load_ctx.fd = fd;