diff --git a/src/glue.c b/src/glue.c
index 2735e4830383d646e5151f94bc36971a4656ad6d..f1e086a5fa4d3153b9382ea6c09449f933e90e48 100644
--- a/src/glue.c
+++ b/src/glue.c
@@ -55,6 +55,13 @@ HParsedToken *h_make_seq(HArena *arena)
   return ret;
 }
 
+HParsedToken *h_make_seqn(HArena *arena, size_t n)
+{
+  HParsedToken *ret = h_make_(arena, TT_SEQUENCE);
+  ret->seq = h_carray_new_sized(arena, n);
+  return ret;
+}
+
 HParsedToken *h_make_bytes(HArena *arena, size_t len)
 {
   HParsedToken *ret = h_make_(arena, TT_BYTES);
diff --git a/src/glue.h b/src/glue.h
index 90944ea094fc0490aeefad194525b4ea7f652e2d..3125ae07f308b363e25716777cc689c5e6c607c7 100644
--- a/src/glue.h
+++ b/src/glue.h
@@ -173,6 +173,7 @@ const HParsedToken *h_act_flatten(const HParseResult *p);
 
 HParsedToken *h_make(HArena *arena, HTokenType type, void *value);
 HParsedToken *h_make_seq(HArena *arena);  // Makes empty sequence.
+HParsedToken *h_make_seqn(HArena *arena, size_t n);  // Makes empty sequence of expected size n.
 HParsedToken *h_make_bytes(HArena *arena, size_t len);
 HParsedToken *h_make_sint(HArena *arena, int64_t val);
 HParsedToken *h_make_uint(HArena *arena, uint64_t val);
@@ -180,6 +181,7 @@ HParsedToken *h_make_uint(HArena *arena, uint64_t val);
 // Standard short-hands to make tokens in an action.
 #define H_MAKE(TYP, VAL)  h_make(p->arena, TT_ ## TYP, VAL)
 #define H_MAKE_SEQ()      h_make_seq(p->arena)
+#define H_MAKE_SEQN(N)    h_make_seqn(p->arena, N)
 #define H_MAKE_BYTES(LEN) h_make_bytes(p->arena, LEN)
 #define H_MAKE_SINT(VAL)  h_make_sint(p->arena, VAL)
 #define H_MAKE_UINT(VAL)  h_make_uint(p->arena, VAL)