1 files changed, 4 insertions, 0 deletions
diff --git a/op.h b/op.h
index 958529e306..d61198f28c 100644
--- a/op.h
+++ b/op.h
@@ -229,6 +229,10 @@ Deprecated.  Use C<GIMME_V> instead.
   /* OP_RV2[AGH]V, OP_PAD[AH]V, OP_[AH]ELEM, OP_[AH]SLICE OP_AV2ARYLEN,
      OP_R?KEYS, OP_SUBSTR, OP_POS, OP_VEC */
 #define OPpMAYBE_LVSUB		8	/* We might be an lvalue to return */
+
+  /* OP_SUBSTR only */
+#define OPpSUBSTR_REPL_FIRST	16	/* 1st arg is replacement string */
+
   /* OP_PADSV only */
 #define OPpPAD_STATE		16	/* is a "state" pad */
   /* for OP_RV2?V, lower bits carry hints (currently only HINT_STRICT_REFS) */