diff --git a/contrib/hstore_plperl/hstore_plperl.c b/contrib/hstore_plperl/hstore_plperl.c
index b5f72138f17..4977724a1bf 100644
--- a/contrib/hstore_plperl/hstore_plperl.c
+++ b/contrib/hstore_plperl/hstore_plperl.c
@@ -125,8 +125,9 @@ plperl_to_hstore(PG_FUNCTION_ARGS)
 				 errmsg("cannot transform non-hash Perl value to hstore")));
 	hv = (HV *) in;
 
-	pcount = hv_iterinit(hv);
+	(void) hv_iterinit(hv);
 
+	pcount = 64;				/* arbitrary initial guess */
 	pairs = palloc_array(Pairs, pcount);
 
 	i = 0;
@@ -135,6 +136,12 @@ plperl_to_hstore(PG_FUNCTION_ARGS)
 		char	   *key = sv2cstr(HeSVKEY_force(he));
 		SV		   *value = HeVAL(he);
 
+		if (i >= pcount)
+		{
+			pcount *= 2;
+			pairs = repalloc_array(pairs, Pairs, pcount);
+		}
+
 		pairs[i].key = pstrdup(key);
 		pairs[i].keylen = hstoreCheckKeyLen(strlen(pairs[i].key));
 		pairs[i].needfree = true;
@@ -155,7 +162,7 @@ plperl_to_hstore(PG_FUNCTION_ARGS)
 		i++;
 	}
 
-	pcount = hstoreUniquePairs(pairs, pcount, &buflen);
+	pcount = hstoreUniquePairs(pairs, i, &buflen);
 	out = hstorePairs(pairs, pcount, buflen);
 	PG_RETURN_POINTER(out);
 }
diff --git a/src/pl/plperl/plperl.c b/src/pl/plperl/plperl.c
index c50165923a8..d1751c3124c 100644
--- a/src/pl/plperl/plperl.c
+++ b/src/pl/plperl/plperl.c
@@ -1165,6 +1165,10 @@ get_perl_array_ref(SV *sv)
  * if we didn't do it like that, we'd need some other convention for knowing
  * whether we'd already found any scalars (and thus the number of dimensions
  * is frozen).
+ *
+ * Caller is required to have set dims[cur_depth - 1] to the length of the
+ * input array, i.e., av_len(av) + 1.  We make this requirement so as to
+ * avoid reading av_len() twice, which is hazardous for tied arrays.
  */
 static void
 array_to_datum_internal(AV *av, ArrayBuildState **astatep,
@@ -1174,7 +1178,7 @@ array_to_datum_internal(AV *av, ArrayBuildState **astatep,
 {
 	dTHX;
 	int			i;
-	int			len = av_len(av) + 1;
+	int			len = dims[cur_depth - 1];
 
 	for (i = 0; i < len; i++)
 	{