diff --git a/library/kernel/file-system-harness.zig b/library/kernel/file-system-harness.zig
index 80d629f..dce1706 100644
--- a/library/kernel/file-system-harness.zig
+++ b/library/kernel/file-system-harness.zig
@@ -310,8 +310,11 @@ pub fn Server(comptime Engine: type) type {
                     // The failure diagnostic goes to the kernel ring directly, not
                     // through std.log — the mount that failed may be /system/logs
                     // itself, and a routed record would then have nowhere to land.
-                    var line: [96]u8 = undefined;
-                    _ = logging.write(std.fmt.bufPrint(&line, "file-system: could not mount {s}\n", .{m.prefix}) catch "file-system: a mount failed\n");
+                    // Three appends rather than a formatted line so there is no
+                    // scratch buffer (and so no fixed length to justify).
+                    _ = logging.write("file-system: could not mount ");
+                    _ = logging.write(m.prefix);
+                    _ = logging.write("\n");
                 }
             }
             mounted = true;