diff --git a/bedstead.c b/bedstead.c
index 88934eb..8f96e0b 100644
--- a/bedstead.c
+++ b/bedstead.c
@@ -215,8 +215,13 @@ static struct weight const *weight = &weights[0];
 
 static struct glyph {
 	union {
-		/* Top row (and left column) don't appear in ROM. */
-	        unsigned char data[YSIZE - 1];
+		/*
+		 * Top row (and left column) don't appear in ROM.  But
+		 * we allow an extra byte so that string constants can
+		 * write a terminating null.  Without that, GCC 15
+		 * generates a warning that the string might be
+		 * unterminated. */
+	        unsigned char data[YSIZE - 1 + 1];
 		char const *alias_of;
 		int subr_idx;
 	};