diff --git a/src/lj_cconv.c b/src/lj_cconv.c
index de4938e4..90cd36e3 100644
--- a/src/lj_cconv.c
+++ b/src/lj_cconv.c
@@ -702,6 +702,7 @@ static void cconv_substruct_init(CTState *cts, CType *d, uint8_t *dp,
     } else if (ctype_isxattrib(df->info, CTA_SUBTYPE)) {
       cconv_substruct_init(cts, ctype_rawchild(cts, df),
 			   dp+df->size, o, len, ip);
+      if ((d->info & CTF_UNION)) break;
     }  /* Ignore all other entries in the chain. */
   }
 }
diff --git a/src/lj_crecord.c b/src/lj_crecord.c
index 4e64f431..acd786f5 100644
--- a/src/lj_crecord.c
+++ b/src/lj_crecord.c
@@ -1466,6 +1466,7 @@ void LJ_FASTCALL recff_cdata_arith(jit_State *J, RecordFFData *rd)
       }
     } else if (!tref_isnum(tr)) {
       tr = 0;
+      ct = ctype_get(cts, CTID_P_VOID);
     }
   ok:
     s[i] = ct;