diff --git a/builtin-mailinfo.c b/builtin-mailinfo.c
index 97c1ff9744..fa6e8f90a4 100644
--- a/builtin-mailinfo.c
+++ b/builtin-mailinfo.c
@@ -812,6 +812,7 @@ static void handle_body(void)
 					      np - newline);
 			if (!handle_boundary())
 				return;
+			len = strlen(line);
 		}
 
 		/* Unwrap transfer encoding */