diff --git a/src/glue.c b/src/glue.c
index 58fe4175d4fd326b62c76449449a74768605ca9e..37962e849283951972ed60094345bec62b57434f 100644
--- a/src/glue.c
+++ b/src/glue.c
@@ -106,7 +106,7 @@ HParsedToken *h_make_seqn(HArena *arena, size_t n)
   return ret;
 }
 
-HParsedToken *h_make_bytes(HArena *arena, uint8_t *array, size_t len)
+HParsedToken *h_make_bytes(HArena *arena, const uint8_t *array, size_t len)
 {
   HParsedToken *ret = h_make_(arena, TT_BYTES);
   ret->bytes.len = len;
diff --git a/src/glue.h b/src/glue.h
index 0bbfe9cfa26ec1bb6376ff23aa3b2d6cc3b4e873..31597cd21c829d362e0a66c52a39dfc95b2a3a96 100644
--- a/src/glue.h
+++ b/src/glue.h
@@ -195,7 +195,7 @@ HParsedToken *h_act_ignore(const HParseResult *p, void* user_data);
 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, uint8_t *array, size_t len);
+HParsedToken *h_make_bytes(HArena *arena, const uint8_t *array, size_t len);
 HParsedToken *h_make_sint(HArena *arena, int64_t val);
 HParsedToken *h_make_uint(HArena *arena, uint64_t val);