--- a/lib/tre-parse.c
+++ b/lib/tre-parse.c
@@ -582,16 +582,23 @@
 tre_parse_int(const tre_char_t **regex, const tre_char_t *regex_end)
 {
   int num = -1;
+  int overflow = 0;
   const tre_char_t *r = *regex;
   while (r < regex_end && *r >= L'0' && *r <= L'9')
     {
       if (num < 0)
 	num = 0;
-      num = num * 10 + *r - L'0';
+      if (num <= (INT_MAX - 9) / 10) {
+        num = num * 10 + *r - L'0';
+      } else {
+        /* This digit could cause an integer overflow. We do not return
+         * directly; instead, consume all remaining digits. */
+        overflow = 1;
+      }
       r++;
     }
   *regex = r;
-  return num;
+  return overflow ? -1 : num;
 }