compositor-x11: Fix a memory leak.
diff --git a/src/compositor-x11.c b/src/compositor-x11.c
index 2349936..e616f45 100644
--- a/src/compositor-x11.c
+++ b/src/compositor-x11.c
@@ -1239,6 +1239,7 @@
 		if (output_name)
 			free(output_name);
 		output_name = NULL;
+		free(output);
 		goto err_free;
 	}