2 files changed, 3 insertions, 4 deletions
diff --git a/src/scanners.c b/src/scanners.c
index c0df18b..ae4125f 100644
--- a/src/scanners.c
+++ b/src/scanners.c
@@ -7,10 +7,9 @@ bufsize_t _scan_at(bufsize_t (*scanner)(const unsigned char *), cmark_chunk *c,
                    bufsize_t offset) {
   bufsize_t res;
   unsigned char *ptr = (unsigned char *)c->data;
-  unsigned char zero = '\0';
 
-  if (ptr == NULL) {
-    res = scanner(&zero);
+  if (ptr == NULL || offset > c->len) {
+    return 0;
   } else {
     unsigned char lim = ptr[c->len];
 
diff --git a/src/scanners.re b/src/scanners.re
index befe7d0..8176590 100644
--- a/src/scanners.re
+++ b/src/scanners.re
@@ -7,7 +7,7 @@ bufsize_t _scan_at(bufsize_t (*scanner)(const unsigned char *), cmark_chunk *c,
 	bufsize_t res;
 	unsigned char *ptr = (unsigned char *)c->data;
 
-        if (ptr == NULL) {
+        if (ptr == NULL || offset > c->len) {
           return 0;
         } else {
 	  unsigned char lim = ptr[c->len];