diff --git a/src/bfu/style.c b/src/bfu/style.c
index 741282fd..b13402fb 100644
--- a/src/bfu/style.c
+++ b/src/bfu/style.c
@@ -28,7 +28,7 @@ struct bfu_color_entry {
 static struct hash *bfu_colors = NULL;
 
 struct color_pair *
-get_bfu_color(struct terminal *term, char *stylename)
+get_bfu_color(struct terminal *term, const char *stylename)
 {
 	static enum color_mode last_color_mode;
 	struct bfu_color_entry *entry;
diff --git a/src/bfu/style.h b/src/bfu/style.h
index aeb03610..4af54258 100644
--- a/src/bfu/style.h
+++ b/src/bfu/style.h
@@ -23,7 +23,7 @@ struct terminal;
  * @return		A color pair matching the stylename or NULL.
  */
 struct color_pair *
-get_bfu_color(struct terminal *term, char *stylename);
+get_bfu_color(struct terminal *term, const char *stylename);
 
 /** Cleanup after the BFU style cache
  *