diff --git a/Fonderie/sfx.c b/Fonderie/sfx.c
index c48ac87..060deaf 100644
--- a/Fonderie/sfx.c
+++ b/Fonderie/sfx.c
@@ -324,6 +324,8 @@ if (offset<0 || offset>=pimg->width) {
 	return -66;
 	}
 
+fprintf(stderr, "ERROR: %s not implemented\n", __func__);
+
 return -1;
 }
 /* -------------------------------------------------------------- */