diff --git a/programmer.h b/programmer.h
index 1eb0a99..8de42bc 100644
--- a/programmer.h
+++ b/programmer.h
@@ -122,7 +122,7 @@
 
 extern const struct programmer_entry programmer_table[];
 
-int programmer_init(enum programmer prog, char *param);
+int programmer_init(enum programmer prog, const char *param);
 int programmer_shutdown(void);
 
 enum bitbang_spi_master_type {