diff --git a/src/md4c.c b/src/md4c.c
index 3677c0e..43d7655 100644
--- a/src/md4c.c
+++ b/src/md4c.c
@@ -2992,6 +2992,42 @@ md_is_autolink(MD_CTX* ctx, OFF beg, OFF max_end, OFF* p_end, int* p_missing_mai
     return FALSE;
 }
 
+/***********************************************
+ ***  Helpers for identifying opener/closer  ***
+ ***********************************************/
+enum {
+    SP_WHITESPACE_OR_PUNCT_BEFORE   = 1 << 0,
+    SP_WHITESPACE_OR_PUNCT_AFTER    = 1 << 1,
+    SP_BEGINS_LINE                  = 1 << 2,
+    SP_ENDS_LINE                    = 1 << 3,
+};
+
+static inline unsigned
+md_get_potential_flags(MD_CTX *ctx, OFF off, OFF tmp, OFF line_beg, OFF line_end)
+{
+    unsigned sp, flags;
+
+    sp = flags = 0;
+
+    if(ISUNICODEWHITESPACEBEFORE(off)  ||  ISUNICODEPUNCTBEFORE(off))
+        sp |= SP_WHITESPACE_OR_PUNCT_BEFORE;
+    if(ISUNICODEWHITESPACE(tmp)  ||  ISUNICODEPUNCT(tmp))
+        sp |= SP_WHITESPACE_OR_PUNCT_AFTER;
+    if(off == line_beg)
+        sp |= SP_BEGINS_LINE;
+    if(tmp == line_end)
+        sp |= SP_ENDS_LINE;
+
+    if (sp) {
+        if(!(sp & (SP_ENDS_LINE | SP_WHITESPACE_OR_PUNCT_AFTER)))
+            flags |= MD_MARK_POTENTIAL_OPENER;
+        if(!(sp & (SP_BEGINS_LINE | SP_WHITESPACE_OR_PUNCT_BEFORE)))
+            flags |= MD_MARK_POTENTIAL_CLOSER;
+    }
+
+    return flags;
+}
+
 static int
 md_collect_marks(MD_CTX* ctx, const MD_LINE* lines, int n_lines, int table_mode)
 {