diff --git a/usr.sbin/bhyve/qemu_fwcfg.h b/usr.sbin/bhyve/qemu_fwcfg.h
--- a/usr.sbin/bhyve/qemu_fwcfg.h
+++ b/usr.sbin/bhyve/qemu_fwcfg.h
@@ -18,6 +18,6 @@
 	uint8_t *data;
 };
 
-int qemu_fwcfg_add_file(const uint8_t name[QEMU_FWCFG_MAX_NAME],
+int qemu_fwcfg_add_file(const char *name,
     const uint32_t size, void *const data);
 int qemu_fwcfg_init(struct vmctx *const ctx);
diff --git a/usr.sbin/bhyve/qemu_fwcfg.c b/usr.sbin/bhyve/qemu_fwcfg.c
--- a/usr.sbin/bhyve/qemu_fwcfg.c
+++ b/usr.sbin/bhyve/qemu_fwcfg.c
@@ -261,9 +261,11 @@
 }
 
 int
-qemu_fwcfg_add_file(const uint8_t name[QEMU_FWCFG_MAX_NAME],
-    const uint32_t size, void *const data)
+qemu_fwcfg_add_file(const char *name, const uint32_t size, void *const data)
 {
+	if (strlen(name) >= QEMU_FWCFG_MAX_NAME)
+		return (EINVAL);
+
 	/*
 	 * QEMU specifies count as big endian.
 	 * Convert it to host endian to work with it.