diff --git a/sys/gdb/gdb_main.c b/sys/gdb/gdb_main.c
index e184928b0445..70ffe0719c45 100644
--- a/sys/gdb/gdb_main.c
+++ b/sys/gdb/gdb_main.c
@@ -361,9 +361,7 @@ init_qXfer_ctx(struct qXfer_context *qx, uintmax_t len)
 }
 
 /*
- * dst must be 2x strlen(max_src) + 1.
- *
- * Squashes invalid XML characters down to _.  Sorry.  Then escapes for GDB.
+ * Squashes special XML and GDB characters down to _.  Sorry.
  */
 static void
 qXfer_escape_xmlattr_str(char *dst, size_t dstlen, const char *src)
@@ -384,8 +382,18 @@ qXfer_escape_xmlattr_str(char *dst, size_t dstlen, const char *src)
 
 		/* GDB escape. */
 		if (strchr(forbidden, c) != NULL) {
+			/*
+			 * It would be nice to escape these properly, but to do
+			 * it correctly we need to escape them in the transmit
+			 * layer, potentially doubling our buffer requirements.
+			 * For now, avoid breaking the protocol by squashing
+			 * them to underscore.
+			 */
+#if 0
 			*dst++ = '}';
 			c ^= 0x20;
+#endif
+			c = '_';
 		}
 		*dst++ = c;
 	}