diff --git a/src/stringprep/stringprep_drv.c b/src/stringprep/stringprep_drv.c
index 8007fb5f8..a2e5e8fc9 100644
--- a/src/stringprep/stringprep_drv.c
+++ b/src/stringprep/stringprep_drv.c
@@ -369,7 +369,7 @@ static int stringprep_erl_control(ErlDrvData drv_data,
       }
       last_ral = info & D1Mask;
       have_ral = have_ral || last_ral;
-      have_l = info & D2Mask;
+      have_l |= info & D2Mask;
       ADD_UCHAR(ruc);
    }