diff --git a/src/regexp_bt.c b/src/regexp_bt.c
index b71b862..78be2b5 100644
--- a/src/regexp_bt.c
+++ b/src/regexp_bt.c
@@ -4568,6 +4568,8 @@
 
 	cleanup_zsubexpr();
 	re_extmatch_out = make_extmatch();
+	if (re_extmatch_out == NULL)
+	    return 0;
 	for (i = 0; i < NSUBEXP; i++)
 	{
 	    if (REG_MULTI)
diff --git a/src/regexp_nfa.c b/src/regexp_nfa.c
index fb512f9..a288ea4 100644
--- a/src/regexp_nfa.c
+++ b/src/regexp_nfa.c
@@ -7070,6 +7070,8 @@
     {
 	cleanup_zsubexpr();
 	re_extmatch_out = make_extmatch();
+	if (re_extmatch_out == NULL)
+	    return 0;
 	// Loop over \z1, \z2, etc.  There is no \z0.
 	for (i = 1; i < subs.synt.in_use; i++)
 	{
diff --git a/src/version.c b/src/version.c
index 88ea924..3c2c49b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -743,6 +743,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    33,
+/**/
     32,
 /**/
     31,