diff --git a/marshal.h b/marshal.h
index 20094289..515f0e53 100644
--- a/marshal.h
+++ b/marshal.h
@@ -173,8 +173,7 @@ void BinarySink_put_uint64(BinarySink *, uint64_t);
 void BinarySink_put_string(BinarySink *, const void *data, size_t len);
 void BinarySink_put_stringpl(BinarySink *, ptrlen);
 void BinarySink_put_stringz(BinarySink *, const char *str);
-struct strbuf;
-void BinarySink_put_stringsb(BinarySink *, struct strbuf *);
+void BinarySink_put_stringsb(BinarySink *, strbuf *);
 void BinarySink_put_asciz(BinarySink *, const char *str);
 bool BinarySink_put_pstring(BinarySink *, const char *str);
 void BinarySink_put_mp_ssh1(BinarySink *bs, mp_int *x);
diff --git a/utils/marshal.c b/utils/marshal.c
index 84d1391f..534ecf50 100644
--- a/utils/marshal.c
+++ b/utils/marshal.c
@@ -79,7 +79,7 @@ void BinarySink_put_stringz(BinarySink *bs, const char *str)
     BinarySink_put_string(bs, str, strlen(str));
 }
 
-void BinarySink_put_stringsb(BinarySink *bs, struct strbuf *buf)
+void BinarySink_put_stringsb(BinarySink *bs, strbuf *buf)
 {
     BinarySink_put_string(bs, buf->s, buf->len);
     strbuf_free(buf);