diff --git a/src/upb_serialize.h b/src/upb_serialize.h
index e1468dee4a..0a057c5365 100644
--- a/src/upb_serialize.h
+++ b/src/upb_serialize.h
@@ -195,6 +195,9 @@ INLINE size_t upb_get_tag_size(uint32_t fieldnum) {
   return upb_v_uint64_t_size((uint64_t)fieldnum << 3);
 }
 
+upb_status_t upb_serialize_value(uint8_t *buf, uint8_t *end, upb_field_type_t ft,
+                                 union upb_value_ptr v, uint8_t **outbuf);
+
 #ifdef __cplusplus
 }  /* extern "C" */
 #endif
diff --git a/tests/tests.c b/tests/tests.c
index 442e35723f..497910f571 100644
--- a/tests/tests.c
+++ b/tests/tests.c
@@ -4,10 +4,11 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include "descriptor.c"
-#include "upb_enum.c"
-#include "upb_parse.c"
 #include "upb_context.c"
+#include "upb_enum.c"
 #include "upb_msg.c"
+#include "upb_parse.c"
+#include "upb_serialize.c"
 #include "upb_table.c"
 #include "upb_text.c"