diff --git a/src/main/common/printf.c b/src/main/common/printf.c
index 7b740c019..a35f6e1c2 100644
--- a/src/main/common/printf.c
+++ b/src/main/common/printf.c
@@ -147,6 +147,9 @@ int tfp_format(void *putp, putcf putf, const char *fmt, va_list va)
             case '%':
                 putf(putp, ch); written++;
                 break;
+            case 'n':
+                *va_arg(va, int*) = written;
+                break;
             default:
                 break;
             }